The effect of the delivery of vascular endothelial growth factor and bone morphogenic protein-2 to osteoprogenitor cell populations on bone formation (original) (raw)
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Biomaterials, 2008
The capacity to deliver, temporally, bioactive growth factors in combination with appropriate progenitor and stem cells to sites of tissue regeneration promoting angiogenesis and osteogenesis offers therapeutic opportunities in regenerative medicine. We have examined the bone regenerative potential of encapsulated vascular endothelial growth factor (VEGF 165 ) biodegradable poly(DL-lactic acid) (PLA) scaffolds created using supercritical CO 2 fluid technology to encapsulate and release solvent-sensitive and thermolabile growth factors in combination with human bone marrow stromal cells (HBMSC) implanted in a mouse femur segmental defect (5 mm) for 4 weeks. HBMSC seeded on VEGF encapsulated PLA scaffolds showed significant bone regeneration in the femur segmental defect compared to the scaffold alone and scaffold seeded with HBMSC as analysed by indices of increased bone volume (BV mm 3 ), trabecular number (Tb.N/mm) and reduced trabecular separation (Tb.Sp. mm) in the defect region using micro-computed tomography. Histological examination confirmed significant new bone matrix in the HBMSC seeded VEGF encapsulated scaffold group as evidenced by Sirius red/alcian blue and Goldner's trichrome staining and type I collagen immunocytochemistry expression in comparison to the other groups. These studies demonstrate the ability to deliver, temporally, a combination of VEGF released from scaffolds with seeded HBMSC to sites of bone defects, results in enhanced regeneration of a bone defect.
Bulletin of the National Research Centre
Background Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodeling, and repair. Vascular endothelial growth factor (VEGF) is an essential mediator during the process of angiogenesis. The bone morphogenetic protein (BMP-2) family of growth factors plays critical roles in bone formation. VEGF has the potential to enhance BMPs-induced bone formation. Purpose This study attempted to assess VEGF and BMP-2 reflecting the effect of hybrid bio-composite scaffold on bone healing in dogs and evaluate the quality of the healing process radiologically. Methods This study was conducted on 12 adult mongrel dogs. All dogs were divided into four equal groups (n = 3 each): chitosan non-medicated (CH) (NM), chitosan medicated (CH) (M), chitosan bioglass non-medicated (CH.BG) (NM), and Chitosan Bioglass Medicated (CH.BG) (M). VEGF and BMP-2 were evaluated during fracture healing. Results Results have showed a non-significant decrease in serum VEGF...
Journal of Hard Tissue Biology, 2018
In bone tissue engineering, angiogenesis is closely associated with osteogenesis where reciprocal interactions between endothelial and osteoblast cells play an important role in bone regeneration. Over-expression of the angiogenesisrelated gene due to a higher dose of vascular endothelial growth factor (VEGF) protein can inhibit osteogenesis process at mRNA level. To study the eff ect of controlled released of the VEGF protein incorporating fi brin glue (FG) treated with fabricated porous biphasic calcium phosphate (BCP) on osteogenesis gene (BMP-2) and angiogenesis gene (VEGF) on dental stem cells (DSCs) at mRNA level. DSCs were treated with two diff erent modalities; VEGF protein incorporated FG, and VEGF protein incorporated FG added-BCP treated media. The cells were harvested at four diff erent time intervals (day 3, day 7, day 10 and day 14) and were subjected to RNA isolation using the RNA extraction kit. This was followed by performing one step-reverse transcriptase-PCR (RT-PCR) to amplify the osteogenesis BMP-2 gene, angiogenesis VEGF gene and the osteoblast-specifi c transcription factor expression Osterix (Osx) with and without the controlled release of VEGF protein. The RT-PCR products were then electrophoresed. The gel image was captured using Image Analyser. Controlled release of VEGF protein using FG as a natural delivery system, using a single growth factor, show a signifi cantly enhanced osteogenesis BMP-2 gene and angiogenesis VEGF gene with a high expression of Osx compare with non-delivered free VEGF protein treated groups. FG is a biocompatible material that could be employed as a delivery vehicle for controlled release of VEGF protein single or dual release in bone tissue engineering strategy and design of the study. Application of this method for using FG is mixing with a porous ceramic scaff old loading with the growth factors is a convenient and promising strategy for improving osteogenesis and angiogenesis processes of reconstruction critical-sized bone defects and might change the scope of modern surgery.
Biomaterials, 2011
The treatment of challenging fractures and large osseous defects presents a formidable problem for orthopaedic surgeons. Tissue engineering/regenerative medicine approaches seek to solve this problem by delivering osteogenic signals within scaffolding biomaterials. In this study, we introduce a hybrid growth factor delivery system that consists of an electrospun nanofiber mesh tube for guiding bone regeneration combined with peptide-modified alginate hydrogel injected inside the tube for sustained growth factor release. We tested the ability of this system to deliver recombinant bone morphogenetic protein-2 (rhBMP-2) for the repair of critically-sized segmental bone defects in a rat model. Longitudinal μ-CT analysis and torsional testing provided quantitative assessment of bone regeneration. Our results indicate that the hybrid delivery system resulted in consistent bony bridging of the challenging bone defects. However, in the absence of rhBMP-2, the use of nanofiber mesh tube and alginate did not result in substantial bone formation. Perforations in the nanofiber mesh accelerated the rhBMP-2 mediated bone repair, and resulted in functional restoration of the regenerated bone. μ-CT based angiography indicated that perforations did not significantly affect the revascularization of defects, suggesting that some other interaction with the tissue surrounding the defect such as improved infiltration of osteoprogenitor cells contributed to the observed differences in repair. Overall, our results indicate that the hybrid alginate/nanofiber mesh system is a promising growth factor delivery strategy for the repair of challenging bone injuries.
2009
VEGF and its receptors constitute the key signaling system for angiogenic activity in tissue formation, but a direct implication of the growth factor in the recruitment, survival and activity of bone forming cells has also emerged. For this reason, we developed a composite (alginate/chitosan/PLA-H) system that controls the release kinetics of incorporated VEGF to enhance neovascularization in bone healing. VEGF release kinetics and tissue distribution were determined using iodinated (125 I) growth factor. VEGF was firstly encapsulated in alginate microspheres. To reduce the high in vitro burst release, the microspheres were included in scaffolds. Matrices were prepared with alginate (A-1, A-2), chitosan (CH-1, CH-2) or by coating the CH-1 matrix with a PLA-H (30 kDa) film (CH-1-PLA), the latter one optimally reducing the in vitro and in vivo burst effect. The VEGF in vitro release profile from CH-1-PLA was characterized by a 13% release within the first 24 h followed by a constant release rate throughout 5 weeks. For VEGF released from composite scaffolds in vitro, bioactivity was maintained above 90% of the expected value. Despite the fact that the in vivo release rate was slightly faster, a good in vitro-in vivo correlation was found. The VEGF released from CH-1 and CH-1-PLA matrices implanted into the femurs of rats remained located around the implantation site with a negligible systemic exposure. These scaffolds provided a bone local GF concentration above 10 ng/g during 2 and 5 weeks, respectively, in accordance to the in vivo release kinetics. Our data show that the incorporation of VEGF into the present scaffolds allows for a controlled release rate and localization of the GF within the bone defect.
VEGF-controlled release within a bone defect from alginate/chitosan/PLA-H scaffolds
European Journal of Pharmaceutics and Biopharmaceutics, 2009
a b s t r a c t VEGF and its receptors constitute the key signaling system for angiogenic activity in tissue formation, but a direct implication of the growth factor in the recruitment, survival and activity of bone forming cells has also emerged. For this reason, we developed a composite (alginate/chitosan/PLA-H) system that controls the release kinetics of incorporated VEGF to enhance neovascularization in bone healing. VEGF release kinetics and tissue distribution were determined using iodinated ( 125 I) growth factor. VEGF was firstly encapsulated in alginate microspheres. To reduce the high in vitro burst release, the microspheres were included in scaffolds. Matrices were prepared with alginate (A-1, A-2), chitosan (CH-1, CH-2) or by coating the CH-1 matrix with a PLA-H (30 kDa) film (CH-1-PLA), the latter one optimally reducing the in vitro and in vivo burst effect. The VEGF in vitro release profile from CH-1-PLA was characterized by a 13% release within the first 24 h followed by a constant release rate throughout 5 weeks. For VEGF released from composite scaffolds in vitro, bioactivity was maintained above 90% of the expected value. Despite the fact that the in vivo release rate was slightly faster, a good in vitro-in vivo correlation was found. The VEGF released from CH-1 and CH-1-PLA matrices implanted into the femurs of rats remained located around the implantation site with a negligible systemic exposure. These scaffolds provided a bone local GF concentration above 10 ng/g during 2 and 5 weeks, respectively, in accordance to the in vivo release kinetics. Our data show that the incorporation of VEGF into the present scaffolds allows for a controlled release rate and localization of the GF within the bone defect.
Pharmacy Education, 2023
The percentage of ageing individuals above 65 years old is expected to increase by 2040 as speculated by the Department of Statistics, Malaysia (DOSM) (Rashid et al, 2016). The elderly population in Malaysia is expected to be 15% of the total population (Tengku, 2015). Hence, an osteoporotic fracture will be a significant threat due to the increasing number of ageing populations. The osteoporosis-associated bone disorder caused by trauma, severe infection, tumour resection, and skeleton abnormalities may cause the formation of critical-size bone defects. These may require bone grafting transplantation as an intervention technique. Autograft involves harvesting the patient's bone and transplanting it to the fracture sites while allograft involves harvesting bone from one individual and transplanting it into another individual within the same species. Both techniques pose some limitations such as a high risk of immunological reactions, the transmission of infection, and donor-site injury (Oryan et al., 2014). This limitation has led to the development of engineered bone tissue as a potential alternative to the conventional use of bone grafts due to their unlimited supply and their ability in hindering disease transmission. Engineered bone tissue involves the development of new functional bone to induce regeneration via a synergistic combination of the biomaterial scaffold, cells, and biochemical factors (Bouet et al, 2015). A scaffold acts as a vital part of engineered bone tissue to mimic the structure and function of the natural bone Keywords Bone Bone morphogenetic protein-2 (BMP-2) Hydroxyapatite (HA) Synergistic effect Vascular endothelial growth factor (VEGF)
Effect of local sequential VEGF and BMP-2 delivery on ectopic and orthotopic bone regeneration
Biomaterials, 2009
Bone regeneration is a coordinated cascade of events regulated by several cytokines and growth factors. Angiogenic growth factors are predominantly expressed during the early phases for re-establishment of the vascularity, whereas osteogenic growth factors are continuously expressed during bone formation and remodeling. Since vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMPs) are key regulators of angiogenesis and osteogenesis during bone regeneration, the aim of this study was to investigate if their sequential release could enhance BMP-2-induced bone formation. A composite consisting of poly(lactic-co-glycolic acid) microspheres loaded with BMP-2 embedded in a poly(propylene) scaffold surrounded by a gelatin hydrogel loaded with VEGF was used for the sequential release of the growth factors. Empty composites or composites loaded with VEGF and/or BMP-2 were implanted ectopically and orthotopically in Sprague-Dawley rats (n ¼ 9). Following implantation, the local release profiles were determined by measuring the activity of 125 I-labeled growth factors using scintillation probes. After 8 weeks blood vessel and bone formation were analyzed using microangiography, mCT and histology. The scaffolds exhibited a large initial burst release of VEGF within the first 3 days and a sustained release of BMP-2 over the full 56-day implantation period. Although VEGF did not induce bone formation, it did increase the formation of the supportive vascular network (p ¼ 0.03) in ectopic implants. In combination with local sustained BMP-2 release, VEGF significantly enhanced ectopic bone formation compared to BMP-2 alone (p ¼ 0.008). In the orthotopic defects, no effect of VEGF on vascularisation was found, nor was bone formation higher by the combination of growth factors, compared to BMP-2 alone. This study demonstrates that a sequential angiogenic and osteogenic growth factor release may be beneficial for the enhancement of bone regeneration.
Journal of Tissue Engineering and Regenerative Medicine, 2012
Regeneration of cartilage defects can be accelerated by localized delivery of appropriate growth factors (GFs) from scaffolds. In the present study we analysed the in vitro and in vivo release rates and delivery efficacies of transforming growth factor-b1 (TGFb1) and bone morphogenetic protein-2 (BMP-2) from a bilayered system, applied for osteochondral defect repair in a rabbit model. A bone-orientated, porous PLGA cylinder was overlaid with GF containing PLGA microspheres, dispersed in an alginate matrix. Four microsphere formulations were incorporated: (a) blank ones; (b) microspheres containing 50 ng TGFb1; (c) microspheres containing 2.5 mg BMP-2; and (d) microspheres containing 5 mg BMP-2. Release kinetics and tissue distributions were determined using iodinated ( 125 I) GFs. Bioactivity of in vitro released BMP-2 and TGFb1 was confirmed in cell-based assays. In vivo release profiles indicated good GF release control. 20% of BMP-2 and 15% of TGFb1 were released during the first day. Virtually the total dose was delivered at the end of week 6. Significant histological differences were observed between untreated and GF-treated specimens, there being especially relevant short-term outcomes with 50 ng TGFb1 and 5 mg BMP-2. Although the evaluation scores for the newly formed cartilage did not differ significantly, 5 mg BMP-2 gave rise to higher quality cartilage with improved surface regularity, tissue integration and increased collagen-type II and aggrecan immunoreactivity 2 weeks post-implantation. Hence, the bilayered system controlled GF release rates and led to preserved cartilage integrity from 12 weeks up to at least 24 weeks. Copyright
Bone regeneration and vascularization with porous PLGA scaffolds loaded with VEGF (0.35 and 1.75 lg) and BMP-2 (3.5 and 17.5 lg), incorporated in PLGA microspheres, or the combination of either dose of BMP-2 with the low dose of VEGF were investigated in an intramedullary femur defect in rabbits. The system was designed to control growth factor (GF) release and maintain the GFs localized within the defect. An incomplete release was observed in vitro whereas in vivo VEGF and BMP-2 were totally delivered during 3 and 4 weeks, respectively. A weak synergistic effect of the dual delivery of VEGF and BMP-2 (high dose) was found by 4 weeks. However, the absence of an apparent synergistic long-term effect (12 weeks) of the combination over BMP-2 alone suggests that more work has to be done to optimize VEGF dose, sequential presentation, and the ratio of the two GFs to obtain a beneficial bone repair response.