T. Chansakul - Academia.edu (original) (raw)
Papers by T. Chansakul
Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological fu... more Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological functions found in many tissues, including cartilage. HA has been incorporated in a number of biomaterial and scaffold systems. However, HA in the material may be difficult to control if it is not chemically modified and chemical modification of HA may negatively impact biological function. In this study, we developed a poly(ethylene glycol) hydrogel with noncovalent HA-binding capabilities and evaluated its ability to support cartilage formation in vitro and in an articular defect model. Chondrogenic differentiation of mesenchymal stem cells encapsulated in the HA-interactive scaffolds containing various amounts of exogenous HA was evaluated. The HA-binding hydrogel without exogenous HA produced the best cartilage as determined by biochemical content (glysocaminoglycan and collagen), histology (Safranin O and type II collagen staining), and gene expression analysis for aggrecan, type I collagen, type II collagen, and sox-9. This HA-binding formulation was then translated to an osteochondral defect model in the rat knee. After 6 weeks, histological analysis demonstrated improved cartilage tissue production in defects treated with the HA-interactive hydrogel compared to noninteractive control scaffolds and untreated defects. In addition to the tissue repair in the defect space, the Safranin O staining in cartilage tissue surrounding the defect was greater in treatment groups where the HA-binding scaffold was applied. In sum, incorporation of a noncovalent HA-binding functionality into biomaterials provides an ability to interact with local or exogenous HA, which can then impact tissue remodeling and ultimately new tissue production.
AJR. American journal of roentgenology, 2012
The objectives of this article are to highlight the imaging findings of tumor recurrence and othe... more The objectives of this article are to highlight the imaging findings of tumor recurrence and other long-term potential sequelae after breast-conserving surgery and radiation therapy, including increased risk of infection and radiation-induced malignancies. The role of MRI as a problem-solving tool in evaluating the conservatively treated breast will also be discussed. Imaging the treated breast presents challenges because of its limited compressibility and overlapping features of benign posttreatment alterations and tumor recurrence. After lumpectomy and radiation therapy, mammographic findings such as breast edema, skin thickening, fluid collections, architectural distortion, and calcifications have characteristic sequences of evolution toward stability. Changes in the imaging appearance after stability has been achieved--including increasing asymmetry, an enlarging mass, increasing edema or skin thickening, and the development of pleomorphic calcifications within or near the opera...
… Engineering Part A, 2008
A new type of synthetic hydrogel scaffold that mimics certain aspects of structure and function o... more A new type of synthetic hydrogel scaffold that mimics certain aspects of structure and function of natural extracellular matrix (ECM) has been developed. We previously reported the conjugation of collagen mimetic peptide (CMP) to poly (ethylene oxide) ...
Enhancing the specific differentiation of pluripotent embryonic stem (ES) cells has been a challe... more Enhancing the specific differentiation of pluripotent embryonic stem (ES) cells has been a challenge in the field of tissue engineering. Previously, hepatic cells have been shown to secrete various soluble morphogenic factors to direct mesodermal differentiation of ES cells. In this study, we hypothesized that factors secreted by hepatic cells possess chondrogenic-differentiating effects, and, therefore, the co-culture of hepatic cells would enhance chondrogenesis of ES cells. ES-derived cells (ESDCs) were co-cultured with hepatic cells (HEPA-1C1c7) in three-dimensional bilayered hydrogels. After 3 weeks culture, the histological and biochemical analysis of the HEPA-co-cultured ESDCs revealed a four-fold increase in glycosaminoglycan (GAG) compared to ESDCs cultured alone. This result was supported by real-time PCR analysis, which demonstrated an 80-fold increase in aggrecan expression in co-cultured ESDCs. Additionally, type IIB collagen expression was observed only with co-cultured ESDCs, and immunohistochemical analysis resulted in significantly more positive type II collagen staining with co-cultured ESDCs. Moreover, at day 21, gene expression of other lineages in HEPA-co-cultured ESDCs was either comparable to or lower than those of ESDCs cultured alone. These results indicated that co-culture of ESDCs with hepatic cells significantly enhanced specific chondrogenic differentiation of ESDCs.
Collagen mimetic peptide (CMP) with a specific amino acid sequence, -(Pro-Hyp-Gly)(x)-, forms a t... more Collagen mimetic peptide (CMP) with a specific amino acid sequence, -(Pro-Hyp-Gly)(x)-, forms a triple helix conformation that resembles the native protein structure of natural collagens. CMP previously has been shown to associate with type I collagen molecules and fibers via a strand invasion process. We hypothesized that when poly(ethylene glycol) (PEG) hydrogel, a non-adhesive tissue engineering scaffold, is conjugated with CMP, it may retain cell-secreted collagens and also form physical crosslinks that can be manipulated by cells. A photopolymerizable CMP derivative was synthesized and copolymerized with poly(ethylene oxide) diacrylate to create a novel PEG hydrogel. In a model retention experiment, diffusional loss of type I collagen that was added to the hydrogel was limited. Chondrocytes were encapsulated in the hydrogel to examine its use as a tissue engineering scaffold. After 2 weeks, the biochemical analysis of the CMP-conjugated PEG gel revealed an 87% increase in glycosaminoglycan content and a 103% increase in collagen content compared to that of control PEG hydrogels. The histology and immunohistochemistry analyses also showed increased staining of extracellular matrix. These results indicate that the CMP enhances the tissue production of cells encapsulated in the PEG hydrogel by providing cell-manipulated crosslinks and collagen binding sites that simulate natural extracellular matrix.
American Journal of Roentgenology, 2012
The objectives of this article are to discuss the conventional imaging algorithms after breast-co... more The objectives of this article are to discuss the conventional imaging algorithms after breast-conserving surgery and radiation therapy and to review the expected chronologic imaging appearances of the conservatively treated breast. Imaging the treated breast presents challenges because of its limited compressibility and the overlapping features of benign posttreatment alterations and tumor recurrence. After lumpectomy and radiation therapy, mammographic findings such as breast edema, skin thickening, fluid collections, architectural distortion, and calcifications have characteristic sequences of evolution toward stability. Awareness of these normal chronologic imaging findings for the conservatively treated breast minimizes unnecessary recall from screening and permits early detection of recurrent breast carcinoma.
BACKGROUND AND PURPOSE: Otosclerosis is commonly identified on CT as a focus of hypodensity in th... more BACKGROUND AND PURPOSE: Otosclerosis is commonly identified on CT as a focus of hypodensity in the otic capsule anterior to the oval window. However, otosclerosis can have a sclerotic phase approximating the density of normal bone, making diagnosis challenging. This study assesses differences in otic capsule contour and thickness anterolateral to the anterior margin of the oval window in patients with otosclerosis compared with individuals with normal hearing. MATERIALS AND METHODS: Axial CT of 104 ears with clinically diagnosed otosclerosis and 108 consecutive ears of audiometrically normal individuals were retrospectively reviewed. Two radiologists independently evaluated the pattern of otosclerosis, otic capsule contour, and bone thickness on standardized axial images at the level of the oval window and cochleariform process. Measurements were made from the posterolateral margin of the cochlea to the apex of the otic capsule convex contour just anterolateral to the anterior margin of the oval window. In the absence of a convex contour, the sulcus between the oval window and the cochleariform process was identified, and measurement to the depth of the sulcus was used. Receiver operating characteristic analysis determined the best cutoff value of otic capsule thickness. RESULTS: Mean otic capsule thickness (2 SDs) was 3.08 (0.93) mm and 1.82 (0.31) mm in patients with otosclerosis and individuals with normal hearing, respectively (P Ͻ .001), with excellent interobserver agreement. Otic capsule thickness of Ͼ2.3 mm had 96.2% sensitivity, 100% specificity, 100% positive predictive value, and 96.4% negative predictive value for otosclerosis. A bulging/convex contour of the otic capsule had 68.3% sensitivity, 98.1% specificity, 97.3% positive predictive value, and 76.3% negative predictive value. CONCLUSIONS: Patients with otosclerosis have significantly thicker bone abutting the oval window than individuals with normal hearing.
AJNR. American journal of neuroradiology, 2015
Face transplantation is being performed with increasing frequency. Facial edema, fluid collection... more Face transplantation is being performed with increasing frequency. Facial edema, fluid collections, and lymphadenopathy are common postoperative findings and may be due to various etiologies, some of which are particular to face transplantation. The purpose of this study was to demonstrate how postoperative imaging and image-guided minimally invasive procedures can assist in diagnosing and treating complications arising from face transplantation. Retrospective evaluation of 6 consecutive cases of face transplantation performed at Brigham and Women's Hospital between April 2009 and March 2014 was performed with assessment of postoperative imaging and image-guided procedures, including aspiration of postoperative fluid collection, lymph node biopsy, and treatment of salivary gland leak. Through these cases, we demonstrate that early postoperative imaging and image-guided procedures are key components for the management of complications following face transplantation.
Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological fu... more Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological functions found in many tissues, including cartilage. HA has been incorporated in a number of biomaterial and scaffold systems. However, HA in the material may be difficult to control if it is not chemically modified and chemical modification of HA may negatively impact biological function. In this study, we developed a poly(ethylene glycol) hydrogel with noncovalent HA-binding capabilities and evaluated its ability to support cartilage formation in vitro and in an articular defect model. Chondrogenic differentiation of mesenchymal stem cells encapsulated in the HA-interactive scaffolds containing various amounts of exogenous HA was evaluated. The HA-binding hydrogel without exogenous HA produced the best cartilage as determined by biochemical content (glysocaminoglycan and collagen), histology (Safranin O and type II collagen staining), and gene expression analysis for aggrecan, type I collagen, type II collagen, and sox-9. This HA-binding formulation was then translated to an osteochondral defect model in the rat knee. After 6 weeks, histological analysis demonstrated improved cartilage tissue production in defects treated with the HA-interactive hydrogel compared to noninteractive control scaffolds and untreated defects. In addition to the tissue repair in the defect space, the Safranin O staining in cartilage tissue surrounding the defect was greater in treatment groups where the HA-binding scaffold was applied. In sum, incorporation of a noncovalent HA-binding functionality into biomaterials provides an ability to interact with local or exogenous HA, which can then impact tissue remodeling and ultimately new tissue production.
AJR. American journal of roentgenology, 2012
The objectives of this article are to highlight the imaging findings of tumor recurrence and othe... more The objectives of this article are to highlight the imaging findings of tumor recurrence and other long-term potential sequelae after breast-conserving surgery and radiation therapy, including increased risk of infection and radiation-induced malignancies. The role of MRI as a problem-solving tool in evaluating the conservatively treated breast will also be discussed. Imaging the treated breast presents challenges because of its limited compressibility and overlapping features of benign posttreatment alterations and tumor recurrence. After lumpectomy and radiation therapy, mammographic findings such as breast edema, skin thickening, fluid collections, architectural distortion, and calcifications have characteristic sequences of evolution toward stability. Changes in the imaging appearance after stability has been achieved--including increasing asymmetry, an enlarging mass, increasing edema or skin thickening, and the development of pleomorphic calcifications within or near the opera...
… Engineering Part A, 2008
A new type of synthetic hydrogel scaffold that mimics certain aspects of structure and function o... more A new type of synthetic hydrogel scaffold that mimics certain aspects of structure and function of natural extracellular matrix (ECM) has been developed. We previously reported the conjugation of collagen mimetic peptide (CMP) to poly (ethylene oxide) ...
Enhancing the specific differentiation of pluripotent embryonic stem (ES) cells has been a challe... more Enhancing the specific differentiation of pluripotent embryonic stem (ES) cells has been a challenge in the field of tissue engineering. Previously, hepatic cells have been shown to secrete various soluble morphogenic factors to direct mesodermal differentiation of ES cells. In this study, we hypothesized that factors secreted by hepatic cells possess chondrogenic-differentiating effects, and, therefore, the co-culture of hepatic cells would enhance chondrogenesis of ES cells. ES-derived cells (ESDCs) were co-cultured with hepatic cells (HEPA-1C1c7) in three-dimensional bilayered hydrogels. After 3 weeks culture, the histological and biochemical analysis of the HEPA-co-cultured ESDCs revealed a four-fold increase in glycosaminoglycan (GAG) compared to ESDCs cultured alone. This result was supported by real-time PCR analysis, which demonstrated an 80-fold increase in aggrecan expression in co-cultured ESDCs. Additionally, type IIB collagen expression was observed only with co-cultured ESDCs, and immunohistochemical analysis resulted in significantly more positive type II collagen staining with co-cultured ESDCs. Moreover, at day 21, gene expression of other lineages in HEPA-co-cultured ESDCs was either comparable to or lower than those of ESDCs cultured alone. These results indicated that co-culture of ESDCs with hepatic cells significantly enhanced specific chondrogenic differentiation of ESDCs.
Collagen mimetic peptide (CMP) with a specific amino acid sequence, -(Pro-Hyp-Gly)(x)-, forms a t... more Collagen mimetic peptide (CMP) with a specific amino acid sequence, -(Pro-Hyp-Gly)(x)-, forms a triple helix conformation that resembles the native protein structure of natural collagens. CMP previously has been shown to associate with type I collagen molecules and fibers via a strand invasion process. We hypothesized that when poly(ethylene glycol) (PEG) hydrogel, a non-adhesive tissue engineering scaffold, is conjugated with CMP, it may retain cell-secreted collagens and also form physical crosslinks that can be manipulated by cells. A photopolymerizable CMP derivative was synthesized and copolymerized with poly(ethylene oxide) diacrylate to create a novel PEG hydrogel. In a model retention experiment, diffusional loss of type I collagen that was added to the hydrogel was limited. Chondrocytes were encapsulated in the hydrogel to examine its use as a tissue engineering scaffold. After 2 weeks, the biochemical analysis of the CMP-conjugated PEG gel revealed an 87% increase in glycosaminoglycan content and a 103% increase in collagen content compared to that of control PEG hydrogels. The histology and immunohistochemistry analyses also showed increased staining of extracellular matrix. These results indicate that the CMP enhances the tissue production of cells encapsulated in the PEG hydrogel by providing cell-manipulated crosslinks and collagen binding sites that simulate natural extracellular matrix.
American Journal of Roentgenology, 2012
The objectives of this article are to discuss the conventional imaging algorithms after breast-co... more The objectives of this article are to discuss the conventional imaging algorithms after breast-conserving surgery and radiation therapy and to review the expected chronologic imaging appearances of the conservatively treated breast. Imaging the treated breast presents challenges because of its limited compressibility and the overlapping features of benign posttreatment alterations and tumor recurrence. After lumpectomy and radiation therapy, mammographic findings such as breast edema, skin thickening, fluid collections, architectural distortion, and calcifications have characteristic sequences of evolution toward stability. Awareness of these normal chronologic imaging findings for the conservatively treated breast minimizes unnecessary recall from screening and permits early detection of recurrent breast carcinoma.
BACKGROUND AND PURPOSE: Otosclerosis is commonly identified on CT as a focus of hypodensity in th... more BACKGROUND AND PURPOSE: Otosclerosis is commonly identified on CT as a focus of hypodensity in the otic capsule anterior to the oval window. However, otosclerosis can have a sclerotic phase approximating the density of normal bone, making diagnosis challenging. This study assesses differences in otic capsule contour and thickness anterolateral to the anterior margin of the oval window in patients with otosclerosis compared with individuals with normal hearing. MATERIALS AND METHODS: Axial CT of 104 ears with clinically diagnosed otosclerosis and 108 consecutive ears of audiometrically normal individuals were retrospectively reviewed. Two radiologists independently evaluated the pattern of otosclerosis, otic capsule contour, and bone thickness on standardized axial images at the level of the oval window and cochleariform process. Measurements were made from the posterolateral margin of the cochlea to the apex of the otic capsule convex contour just anterolateral to the anterior margin of the oval window. In the absence of a convex contour, the sulcus between the oval window and the cochleariform process was identified, and measurement to the depth of the sulcus was used. Receiver operating characteristic analysis determined the best cutoff value of otic capsule thickness. RESULTS: Mean otic capsule thickness (2 SDs) was 3.08 (0.93) mm and 1.82 (0.31) mm in patients with otosclerosis and individuals with normal hearing, respectively (P Ͻ .001), with excellent interobserver agreement. Otic capsule thickness of Ͼ2.3 mm had 96.2% sensitivity, 100% specificity, 100% positive predictive value, and 96.4% negative predictive value for otosclerosis. A bulging/convex contour of the otic capsule had 68.3% sensitivity, 98.1% specificity, 97.3% positive predictive value, and 76.3% negative predictive value. CONCLUSIONS: Patients with otosclerosis have significantly thicker bone abutting the oval window than individuals with normal hearing.
AJNR. American journal of neuroradiology, 2015
Face transplantation is being performed with increasing frequency. Facial edema, fluid collection... more Face transplantation is being performed with increasing frequency. Facial edema, fluid collections, and lymphadenopathy are common postoperative findings and may be due to various etiologies, some of which are particular to face transplantation. The purpose of this study was to demonstrate how postoperative imaging and image-guided minimally invasive procedures can assist in diagnosing and treating complications arising from face transplantation. Retrospective evaluation of 6 consecutive cases of face transplantation performed at Brigham and Women's Hospital between April 2009 and March 2014 was performed with assessment of postoperative imaging and image-guided procedures, including aspiration of postoperative fluid collection, lymph node biopsy, and treatment of salivary gland leak. Through these cases, we demonstrate that early postoperative imaging and image-guided procedures are key components for the management of complications following face transplantation.