G. Giavaresi - Academia.edu (original) (raw)

Papers by G. Giavaresi

Research paper thumbnail of New perspectives in rotator cuff tendon regeneration: review of tissue engineered therapies

La Chirurgia degli Organi di Movimento, 2008

Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through ... more Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through replacement of an injured tendon segment. Tendons have very poor spontaneous regenerative capabilities, and despite intensive remodelling, complete regeneration is never achieved and the strength of tendon and ligaments remains as much as 30% lower than normal even months or years following an acute injury. Tendons seem to be the least complex of the connective tissues with respect to their composition and architecture and this leads to the expectation that they would be more amenable to tissue engineered approaches than other tissues. An accurate literature revision was done in order to know the state of the art of tissue engineering therapies in the field of rotator cuff regeneration. The following techniques of tissue engineering were considered: local injection of stem cells or growth factors, gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons to be further transplanted in the lesion site. So far, few experimental or clinical studies have been done on tendon tissue engineering compared to the extensive work on other tissues of orthopaedic interest, such as bone and cartilage. The existing studies are related to the following tissue engineering methodologies: gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons. In our opinion the previously described literature revision showed the necessity for future studies in this area also because of recent advances in biological and bioactive scaffolds.

Research paper thumbnail of Chronic alcohol abuse and endosseous implants: Linkage of in vitro osteoblast dysfunction to titanium osseointegration rate

Toxicology, 2008

Chronic alcohol consumption is associated with pathological effects on bone, and it is correlated... more Chronic alcohol consumption is associated with pathological effects on bone, and it is correlated with the increasing risk of osteoporosis and fractures. The negative effects of alcohol intake also influence bone repair processes and the osseointegration of implants. The aim of the present in vitro study was to investigate the proliferation and synthetic activity of osteoblasts isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapour (EE-OB), and sham-aged rats (SA-OB), when cultured on standard commercially pure Ti (cpTi). Osteoblast proliferation (WST-1), alkaline phosphatase (ALP), osteocalcin (OC), collagen type I (CICP), tumor necrosis factor-␣ (TNF-␣), interleukin-6 (IL-6), and transforming growth factor-␤1 (TGF-␤1) were measured at 1, 7, and 14 days of culture.

Research paper thumbnail of Intermittent exposure to ethanol vapor affects osteoblast behaviour more severely than estrogen deficiency does

Toxicology, 2007

With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to inc... more With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to increase all over the world. Habitual excessive alcohol consumption is associated with pathological effects on bone. The aim of the present in vitro study was to investigate comparatively the proliferation and synthetic activity of osteoblasts (OB) isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapor, sham-aged rats and long-term estrogen deficient rats. Cell proliferation (WST1) and synthesis of alkaline phosphatase (ALP), osteocalcin (OC), collagen I (CICP), transforming growth factor beta1 (TGF-␤1), interleukin-6 (IL-6), tumor necrosis factor alfa (TNF␣) were measured at 3, 7 and 14 days of culture.

Research paper thumbnail of In vivo study on the healing of bone defects treated with bone marrow stromal cells, platelet rich plasma and freeze-dried bone allografts, alone and in combination

Journal of Orthopaedic Research, 2005

The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow strom... more The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow stromal cells (BMSC), platelet-rich plasma (PRP), freeze-dried bone allografts (FDBA) alone and in combination (BMSC þ PRP; FDBA þ BMSC; FDBA þ PRP; FDBA þ PRP þ BMSC) was compared. A critical size defect was created in the distal part of the femurs of 48 adult rabbits. Histology and histomorphometry were used in the evaluation of healing at 2, 4, and 12 weeks after surgery. The healing rate (%) was calculated by measuring the residual bone defect area. Architecture of the newly formed bone was compared with that of bone at the same distal femur area of healthy rabbits. The defect healing rate was higher in PRP þ BMSC, FDBA þ PRP, FDBA þ BMSC, and FDBA þ PRP þ BMSC treatments, while lower values were achieved with PRP treatment at all experimental times. The highest bone-healing rate at 2 weeks was achieved with FDBA þ PRP þ BMSC treatment, which resulted significantly different from PRP (p < 0.05) and BMSC (p < 0.05) treatments. At 4 weeks, the bone-healing rate increased except for PRP treatment. Finally, the bone-healing rate of FDBA þ PRP, FDBA þ BMSC, and FDBA þ PRP þ BMSC was significantly higher than that of PRP at 12 weeks (p < 0.05). At 12 weeks, significant differences still existed between PRP, BMSC, and FDBA groups and normal bone (p < 0.05). These results showed that the combination of FDBA, BMSC and PRP permitted an acceleration in bone healing and bone remodeling processes. ß

Research paper thumbnail of Physical characterization of different-roughness titanium surfaces, with and without hydroxyapatite coating, and their effect on human osteoblast-like cells

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2005

The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (H... more The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (HA) coatings on Ti6Al4V, in view of their application on noncemented orthopedic implants. Two innovative vacuum plasma sprayed (VPS) coatings, the first of ultrahigh rough and dense Ti (PG60, R a ‫؍‬ 74 m) and the second of ultrahigh rough and dense Ti coated with HA (HPG60, R a ‫؍‬ 52 m), have been developed, and the response of osteoblast-like cells (MG-63) seeded on these new coatings was evaluated in comparison to: a low roughness and sandblasted (Ti/SA, R a ‫؍‬ 4m) Ti6Al4V surface; Ti medium (TI01, R a ‫؍‬ 18 m), and high (TI60, R a ‫؍‬ 40m) roughness VPS coatings; and the relative Ti plus HA duplex coatings (HT01, R a ‫؍‬ 12 m and HT60, R a ‫؍‬ 36 m respectively), also obtained by VPS. PG60 coating presented no open porosity, making it dense and potentially intrinsically stronger. Cell adhesion and proliferation on PG60 was similar to those of the smoothest one (Ti/SA) and adhesion on ultrahigh roughness was lower than the medium-and high-roughness coatings, whereas cell proliferation on PG60 was lower than TI60. The HA coating determined significant increases in cell proliferation at medium and high roughness levels when compared to the relative Ti coating, but not compared to the ultrahigh one; all HA-coated surfaces showed a decrease in alkaline phosphatase activity and collagen I production. Surface morphology and the HA coating strongly affected cell behavior. However, ultrahigh values of roughness are not correctly seen by cells, and the presence of HA has no improving effects.

Research paper thumbnail of Muscular Trauma Treatment with the Diode Laser: An Experimental in vivo Study in Rabbit

Journal of Applied Animal Research, 2001

ABSTRACT Guzzardella, G.A., Morrone, G., Giavaresi, G., Rocca, M., Torricelli, P., Fini, M. and G... more ABSTRACT Guzzardella, G.A., Morrone, G., Giavaresi, G., Rocca, M., Torricelli, P., Fini, M. and Giardino, R. 2001. Muscular trauma treatment with the diode laser: An experimental in vivo study in rabbit. J. Appl. Anim. Res., 19: 137–144.An experimental rabbit model of traumatic muscular lesion treated using the low-power laser was assessed using histomorphometric and laboratory tests. Twenty adult New Zealand male rabbits were subjected to muscular trauma under general anaesthesia. Four days after trauma, rabbits in A group started a daily laser therapy, while healing occurred spontaneously in group B animals. The following parameters were analysed on muscular samples: qualitative histological aspect and quantitative histomorphometric evaluation of muscular damage and tissue repair. Results showed a better qualitative and quantitative healing process in traumatised muscles treated with the diode Ga-Al-As low-power laser, if compared to muscles where healing occurred spontaneously. The significant results achieved, demonstrated a relationship between traumatised, muscular tissues and stimulation properties of the laser device, and the rabbit proved to be a valid experimental animal model for transferring data into clinical practice.

Research paper thumbnail of Histomorphometric bone modifications induced by growth hormone treatment in a rabbit model of short bowel syndrome

Biomedicine & Pharmacotherapy, 2004

The effects of recombinant human growth hormone (rhGH) on cancellous and cortical bone were inves... more The effects of recombinant human growth hormone (rhGH) on cancellous and cortical bone were investigated in an experimental rabbit model of short bowel syndrome (SBS). Eighteen young male New Zealand rabbits, 2.0 ± 0.2 kg b.w., were divided into three groups: an SBS Group submitted to a 70% midjejunoileal enterectomy and reanastomosis; an SBS-GH Group undergoing the same surgery and receiving 0.4 mg/kg/day rhGH for 28 days; a Control Group which was sham-operated. Thirty-five days after surgery, all the animals were pharmacologically euthanised and their femurs and L5 vertebrae were used for densitometric and histomorphometric studies. Vertebral and femoral densitometric results showed that the SBS Group presented significantly (P < 0.01) lower values (10-25%) than the Control and SBS-GH Groups. Significant differences in the cancellous histomorphometric parameters, namely the trabecular bone area (-7% to 46%), trabecular thickness (-21% to 34%) and trabecular separation (17-32%), were observed between the SBS Group and the other groups. Both the SBS and SBS-GH Groups showed significantly (P < 0.05) higher values than the Control Group in terms of cross-sectional area (~24%), cortical area (~20%), and periosteal perimeter (~9%), while medullary area (41%) and endocortical perimeter (18%) were significantly higher (P < 0.05) in SBS Group than those of Control Group. The current findings are encouraging and suggest that GH administration in SBS animal model used may improve skeletal tissue remodelling.

Research paper thumbnail of New polymers for drug delivery systems in orthopaedics: in vivo biocompatibility evaluation

Biomedecine & Pharmacotherapy, 2004

The use of biodegradable polymers for drug delivery systems excluded the need for a second operat... more The use of biodegradable polymers for drug delivery systems excluded the need for a second operation to remove the carrier. However, the development of an avascular fibrous capsule, reducing drug release, has raised concern about these polymers in terms of tissue-implant reaction. Five novel polymers were evaluated in vivo after implantation in the rat dorsal subcutis and compared to the reference polycaprolactone (PCL). Poly(cyclohexyl-sebacate) (PCS), poly(L-lactide-b-1,5-dioxepan-2-one-b-L-lactide) (PLLA-PDXO-PLLA), two 3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (D400G and D600G), and a poly(organo)phosphazene (POS-PheOEt:Imidazole) specimens were histologically evaluated in terms of the inflammatory tissue thickness and vascular density at 4 and 12 weeks from surgery. The highest values of inflammatory tissue thickness were observed in D600G (P < 0.01), PCS (P < 0.001) and PLLA-PDXO-PLLA (P < 0.001) at 4 weeks, while POP-PheOEt:Imidazole showed the lowest value of inflammatory tissue thickness (P < 0.05) at 12 weeks. D400G, D600G, PLLA-PDXO-PPLA and POP-PheOEt:Imidazole showed higher (P < 0.001) values of vascular density near the implants in comparison to PCL at 4 weeks. Finally, D400G and D600G increased their vessel densities while POP-PheOEt:Imidazole and the synthetic polyester PLLA-PDXO-PLLA presented similar vessel density values during experimental times. These different behaviours to improve neoangiogenesis without severe inflammatory tissue-responses could be further investigated with drugs in order to obtain time-programmable drug delivery systems for musculoskeletal therapy.

Research paper thumbnail of Mechanical and histomorphometric evaluations of titanium implants with different surface treatments inserted in sheep cortical bone

Biomaterials, 2003

for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric... more for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric investigations were performed at different times on implants inserted into sheep femoral cortical bone to compare the in vivo osseointegration of titanium screws (+ 3.5 Â 7 mm length) with different surface treatments. After 8 weeks of implantation, the push-out force of anodized and hydrothermally treated implants (ANODIC) was significantly higher than that of machined implants (MACH) (36%, po0:0005), whereas a decrease of 39% was observed for acid-etched implants (HF) when compared to other surface treatments. After 12 weeks of implantation, the push-out force values of HF implants were still significantly lower than those observed for MACH (À19%, po0:01) and hydroxyapatite vacuum plasma-sprayed implants (HAVPS, À25%, po0:0005), and the highest push-out force was found in HAVPS (po0:001) implants. After 8 and 12 weeks of implantation, the AI of HF implants was significantly (po0:05) lower (BÀ25%) than that of MACH, HAVPS and ANODIC implants. In conclusion, results appear to confirm that there are no specific differences between ANODIC and HAVPS implants in terms of behavior. Moreover, although MACH implants show some surface contaminating agents, they appear to ensure good osseointegration within 12 weeks both mechanically and histomorphometrically, as do ANODIC and HAVPS implants. However, further studies are required to investigate bone hardness and mineralization around implants. r

Research paper thumbnail of A new austenitic stainless steel with negligible nickel content: an in vitro and in vivo comparative investigation

Biomaterials, 2003

A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni ... more A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni (<0.20%). In previous in vitro and in vivo studies it was compared with conventional SS and Ti6Al4V and shown to be a promising material in orthopedics. Because osteoporosis is a type of pathology very often encountered in implanted patients and can be studied with in vitro models, the purpose of the present study was to evaluate P558 in vitro through comparison of normal (nOB) with osteopenic (oOB) bone-derived primary rat osteoblasts. Osteoblasts were cultured directly on P558 and polystyrene as controls for 72 h. Osteoblast proliferation, adhesion, and activity (ALP, OC, TGF-␤1, and IL-6) were evaluated at 24 and 72 h. Results demonstrated that the growth of nOB and oOB cultured on P558 was not affected negatively when compared to control. Cells on P558 did not show any alteration in terms of adhesion, proliferation, and metabolic marker production in nOB and oOB cultures, and a significant increase in ALP, OC, and TGF-␤1 production was observed. SEM images revealed no alteration in cell morphology. The current findings demonstrate that P558 promotes osteoblast proliferation, activation, and differentiation not only in normal bone, but also in osteopenic bone-derived osteoblasts.

Research paper thumbnail of pO2 measurement in an experimental model of patellar tendon autograft pro-anterior cruciate ligament

The International journal of artificial organs

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of... more Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in "in vivo" ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as...

Research paper thumbnail of New perspectives in rotator cuff tendon regeneration: review of tissue engineered therapies

La Chirurgia degli Organi di Movimento, 2008

Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through ... more Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through replacement of an injured tendon segment. Tendons have very poor spontaneous regenerative capabilities, and despite intensive remodelling, complete regeneration is never achieved and the strength of tendon and ligaments remains as much as 30% lower than normal even months or years following an acute injury. Tendons seem to be the least complex of the connective tissues with respect to their composition and architecture and this leads to the expectation that they would be more amenable to tissue engineered approaches than other tissues. An accurate literature revision was done in order to know the state of the art of tissue engineering therapies in the field of rotator cuff regeneration. The following techniques of tissue engineering were considered: local injection of stem cells or growth factors, gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons to be further transplanted in the lesion site. So far, few experimental or clinical studies have been done on tendon tissue engineering compared to the extensive work on other tissues of orthopaedic interest, such as bone and cartilage. The existing studies are related to the following tissue engineering methodologies: gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons. In our opinion the previously described literature revision showed the necessity for future studies in this area also because of recent advances in biological and bioactive scaffolds.

Research paper thumbnail of Chronic alcohol abuse and endosseous implants: Linkage of in vitro osteoblast dysfunction to titanium osseointegration rate

Toxicology, 2008

Chronic alcohol consumption is associated with pathological effects on bone, and it is correlated... more Chronic alcohol consumption is associated with pathological effects on bone, and it is correlated with the increasing risk of osteoporosis and fractures. The negative effects of alcohol intake also influence bone repair processes and the osseointegration of implants. The aim of the present in vitro study was to investigate the proliferation and synthetic activity of osteoblasts isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapour (EE-OB), and sham-aged rats (SA-OB), when cultured on standard commercially pure Ti (cpTi). Osteoblast proliferation (WST-1), alkaline phosphatase (ALP), osteocalcin (OC), collagen type I (CICP), tumor necrosis factor-␣ (TNF-␣), interleukin-6 (IL-6), and transforming growth factor-␤1 (TGF-␤1) were measured at 1, 7, and 14 days of culture.

Research paper thumbnail of Intermittent exposure to ethanol vapor affects osteoblast behaviour more severely than estrogen deficiency does

Toxicology, 2007

With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to inc... more With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to increase all over the world. Habitual excessive alcohol consumption is associated with pathological effects on bone. The aim of the present in vitro study was to investigate comparatively the proliferation and synthetic activity of osteoblasts (OB) isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapor, sham-aged rats and long-term estrogen deficient rats. Cell proliferation (WST1) and synthesis of alkaline phosphatase (ALP), osteocalcin (OC), collagen I (CICP), transforming growth factor beta1 (TGF-␤1), interleukin-6 (IL-6), tumor necrosis factor alfa (TNF␣) were measured at 3, 7 and 14 days of culture.

Research paper thumbnail of In vivo study on the healing of bone defects treated with bone marrow stromal cells, platelet rich plasma and freeze-dried bone allografts, alone and in combination

Journal of Orthopaedic Research, 2005

The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow strom... more The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow stromal cells (BMSC), platelet-rich plasma (PRP), freeze-dried bone allografts (FDBA) alone and in combination (BMSC þ PRP; FDBA þ BMSC; FDBA þ PRP; FDBA þ PRP þ BMSC) was compared. A critical size defect was created in the distal part of the femurs of 48 adult rabbits. Histology and histomorphometry were used in the evaluation of healing at 2, 4, and 12 weeks after surgery. The healing rate (%) was calculated by measuring the residual bone defect area. Architecture of the newly formed bone was compared with that of bone at the same distal femur area of healthy rabbits. The defect healing rate was higher in PRP þ BMSC, FDBA þ PRP, FDBA þ BMSC, and FDBA þ PRP þ BMSC treatments, while lower values were achieved with PRP treatment at all experimental times. The highest bone-healing rate at 2 weeks was achieved with FDBA þ PRP þ BMSC treatment, which resulted significantly different from PRP (p < 0.05) and BMSC (p < 0.05) treatments. At 4 weeks, the bone-healing rate increased except for PRP treatment. Finally, the bone-healing rate of FDBA þ PRP, FDBA þ BMSC, and FDBA þ PRP þ BMSC was significantly higher than that of PRP at 12 weeks (p < 0.05). At 12 weeks, significant differences still existed between PRP, BMSC, and FDBA groups and normal bone (p < 0.05). These results showed that the combination of FDBA, BMSC and PRP permitted an acceleration in bone healing and bone remodeling processes. ß

Research paper thumbnail of Physical characterization of different-roughness titanium surfaces, with and without hydroxyapatite coating, and their effect on human osteoblast-like cells

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2005

The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (H... more The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (HA) coatings on Ti6Al4V, in view of their application on noncemented orthopedic implants. Two innovative vacuum plasma sprayed (VPS) coatings, the first of ultrahigh rough and dense Ti (PG60, R a ‫؍‬ 74 m) and the second of ultrahigh rough and dense Ti coated with HA (HPG60, R a ‫؍‬ 52 m), have been developed, and the response of osteoblast-like cells (MG-63) seeded on these new coatings was evaluated in comparison to: a low roughness and sandblasted (Ti/SA, R a ‫؍‬ 4m) Ti6Al4V surface; Ti medium (TI01, R a ‫؍‬ 18 m), and high (TI60, R a ‫؍‬ 40m) roughness VPS coatings; and the relative Ti plus HA duplex coatings (HT01, R a ‫؍‬ 12 m and HT60, R a ‫؍‬ 36 m respectively), also obtained by VPS. PG60 coating presented no open porosity, making it dense and potentially intrinsically stronger. Cell adhesion and proliferation on PG60 was similar to those of the smoothest one (Ti/SA) and adhesion on ultrahigh roughness was lower than the medium-and high-roughness coatings, whereas cell proliferation on PG60 was lower than TI60. The HA coating determined significant increases in cell proliferation at medium and high roughness levels when compared to the relative Ti coating, but not compared to the ultrahigh one; all HA-coated surfaces showed a decrease in alkaline phosphatase activity and collagen I production. Surface morphology and the HA coating strongly affected cell behavior. However, ultrahigh values of roughness are not correctly seen by cells, and the presence of HA has no improving effects.

Research paper thumbnail of Muscular Trauma Treatment with the Diode Laser: An Experimental in vivo Study in Rabbit

Journal of Applied Animal Research, 2001

ABSTRACT Guzzardella, G.A., Morrone, G., Giavaresi, G., Rocca, M., Torricelli, P., Fini, M. and G... more ABSTRACT Guzzardella, G.A., Morrone, G., Giavaresi, G., Rocca, M., Torricelli, P., Fini, M. and Giardino, R. 2001. Muscular trauma treatment with the diode laser: An experimental in vivo study in rabbit. J. Appl. Anim. Res., 19: 137–144.An experimental rabbit model of traumatic muscular lesion treated using the low-power laser was assessed using histomorphometric and laboratory tests. Twenty adult New Zealand male rabbits were subjected to muscular trauma under general anaesthesia. Four days after trauma, rabbits in A group started a daily laser therapy, while healing occurred spontaneously in group B animals. The following parameters were analysed on muscular samples: qualitative histological aspect and quantitative histomorphometric evaluation of muscular damage and tissue repair. Results showed a better qualitative and quantitative healing process in traumatised muscles treated with the diode Ga-Al-As low-power laser, if compared to muscles where healing occurred spontaneously. The significant results achieved, demonstrated a relationship between traumatised, muscular tissues and stimulation properties of the laser device, and the rabbit proved to be a valid experimental animal model for transferring data into clinical practice.

Research paper thumbnail of Histomorphometric bone modifications induced by growth hormone treatment in a rabbit model of short bowel syndrome

Biomedicine & Pharmacotherapy, 2004

The effects of recombinant human growth hormone (rhGH) on cancellous and cortical bone were inves... more The effects of recombinant human growth hormone (rhGH) on cancellous and cortical bone were investigated in an experimental rabbit model of short bowel syndrome (SBS). Eighteen young male New Zealand rabbits, 2.0 ± 0.2 kg b.w., were divided into three groups: an SBS Group submitted to a 70% midjejunoileal enterectomy and reanastomosis; an SBS-GH Group undergoing the same surgery and receiving 0.4 mg/kg/day rhGH for 28 days; a Control Group which was sham-operated. Thirty-five days after surgery, all the animals were pharmacologically euthanised and their femurs and L5 vertebrae were used for densitometric and histomorphometric studies. Vertebral and femoral densitometric results showed that the SBS Group presented significantly (P < 0.01) lower values (10-25%) than the Control and SBS-GH Groups. Significant differences in the cancellous histomorphometric parameters, namely the trabecular bone area (-7% to 46%), trabecular thickness (-21% to 34%) and trabecular separation (17-32%), were observed between the SBS Group and the other groups. Both the SBS and SBS-GH Groups showed significantly (P < 0.05) higher values than the Control Group in terms of cross-sectional area (~24%), cortical area (~20%), and periosteal perimeter (~9%), while medullary area (41%) and endocortical perimeter (18%) were significantly higher (P < 0.05) in SBS Group than those of Control Group. The current findings are encouraging and suggest that GH administration in SBS animal model used may improve skeletal tissue remodelling.

Research paper thumbnail of New polymers for drug delivery systems in orthopaedics: in vivo biocompatibility evaluation

Biomedecine & Pharmacotherapy, 2004

The use of biodegradable polymers for drug delivery systems excluded the need for a second operat... more The use of biodegradable polymers for drug delivery systems excluded the need for a second operation to remove the carrier. However, the development of an avascular fibrous capsule, reducing drug release, has raised concern about these polymers in terms of tissue-implant reaction. Five novel polymers were evaluated in vivo after implantation in the rat dorsal subcutis and compared to the reference polycaprolactone (PCL). Poly(cyclohexyl-sebacate) (PCS), poly(L-lactide-b-1,5-dioxepan-2-one-b-L-lactide) (PLLA-PDXO-PLLA), two 3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (D400G and D600G), and a poly(organo)phosphazene (POS-PheOEt:Imidazole) specimens were histologically evaluated in terms of the inflammatory tissue thickness and vascular density at 4 and 12 weeks from surgery. The highest values of inflammatory tissue thickness were observed in D600G (P < 0.01), PCS (P < 0.001) and PLLA-PDXO-PLLA (P < 0.001) at 4 weeks, while POP-PheOEt:Imidazole showed the lowest value of inflammatory tissue thickness (P < 0.05) at 12 weeks. D400G, D600G, PLLA-PDXO-PPLA and POP-PheOEt:Imidazole showed higher (P < 0.001) values of vascular density near the implants in comparison to PCL at 4 weeks. Finally, D400G and D600G increased their vessel densities while POP-PheOEt:Imidazole and the synthetic polyester PLLA-PDXO-PLLA presented similar vessel density values during experimental times. These different behaviours to improve neoangiogenesis without severe inflammatory tissue-responses could be further investigated with drugs in order to obtain time-programmable drug delivery systems for musculoskeletal therapy.

Research paper thumbnail of Mechanical and histomorphometric evaluations of titanium implants with different surface treatments inserted in sheep cortical bone

Biomaterials, 2003

for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric... more for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric investigations were performed at different times on implants inserted into sheep femoral cortical bone to compare the in vivo osseointegration of titanium screws (+ 3.5 Â 7 mm length) with different surface treatments. After 8 weeks of implantation, the push-out force of anodized and hydrothermally treated implants (ANODIC) was significantly higher than that of machined implants (MACH) (36%, po0:0005), whereas a decrease of 39% was observed for acid-etched implants (HF) when compared to other surface treatments. After 12 weeks of implantation, the push-out force values of HF implants were still significantly lower than those observed for MACH (À19%, po0:01) and hydroxyapatite vacuum plasma-sprayed implants (HAVPS, À25%, po0:0005), and the highest push-out force was found in HAVPS (po0:001) implants. After 8 and 12 weeks of implantation, the AI of HF implants was significantly (po0:05) lower (BÀ25%) than that of MACH, HAVPS and ANODIC implants. In conclusion, results appear to confirm that there are no specific differences between ANODIC and HAVPS implants in terms of behavior. Moreover, although MACH implants show some surface contaminating agents, they appear to ensure good osseointegration within 12 weeks both mechanically and histomorphometrically, as do ANODIC and HAVPS implants. However, further studies are required to investigate bone hardness and mineralization around implants. r

Research paper thumbnail of A new austenitic stainless steel with negligible nickel content: an in vitro and in vivo comparative investigation

Biomaterials, 2003

A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni ... more A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni (<0.20%). In previous in vitro and in vivo studies it was compared with conventional SS and Ti6Al4V and shown to be a promising material in orthopedics. Because osteoporosis is a type of pathology very often encountered in implanted patients and can be studied with in vitro models, the purpose of the present study was to evaluate P558 in vitro through comparison of normal (nOB) with osteopenic (oOB) bone-derived primary rat osteoblasts. Osteoblasts were cultured directly on P558 and polystyrene as controls for 72 h. Osteoblast proliferation, adhesion, and activity (ALP, OC, TGF-␤1, and IL-6) were evaluated at 24 and 72 h. Results demonstrated that the growth of nOB and oOB cultured on P558 was not affected negatively when compared to control. Cells on P558 did not show any alteration in terms of adhesion, proliferation, and metabolic marker production in nOB and oOB cultures, and a significant increase in ALP, OC, and TGF-␤1 production was observed. SEM images revealed no alteration in cell morphology. The current findings demonstrate that P558 promotes osteoblast proliferation, activation, and differentiation not only in normal bone, but also in osteopenic bone-derived osteoblasts.

Research paper thumbnail of pO2 measurement in an experimental model of patellar tendon autograft pro-anterior cruciate ligament

The International journal of artificial organs

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of... more Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in "in vivo" ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as...