Yunyu Hu

Although most in vitro studies indicate that transforming growth factor β3 (TGF‐β3) immobilized scaffold is suitable for cartilage tissue engineering, in vivo studies of implanting immobilized scaffold for chondral defect repair are still lacking. This study is to evaluate the potentials of TGF‐β3 immobilized poly‐(lactic‐co‐glycolic acid)‐gelatin/chondroitin sulfate/hyaluronic acid (PLGA‐GCH) hybrid scaffold for cartilage regeneration. The scaffold was fabricated by incorporating GCH micro‐sponges into PLGA frameworks and then crosslinked with TGF‐β3 to mimic natural cartilaginous extra cellular matrix (ECM). In vitro study demonstrated that MSCs proliferated vigorously and produced abundant ECM on scaffold. The immunohistochemistry staining and alcian blue staining confirmed the cartilaginous ECM production. The chondrogenic differentiation of MSCs on scaffold was proved by the expression of collagen II gene in mRNA and protein level. Then MSCs/TGF‐β3 immobilized scaffolds were implanted in rabbits for chondral defects repair. After eight weeks, histological observation showed that differentiated MSCs were located in lacunae within the metachromatic staining matrix and exhibited typical chondrocyte morphology. Histological grading scores also indicated the congruent cartilage was regenerated. In conclusion, the TGF‐β3 immobilized PLGA‐GCH hybrid scaffold has great potential in constructing the tissue‐engineered cartilage. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

Contaminated or infected bone defects and osteomyelitis after trauma are frequently encountered in clinical practice. It is difficult to make a successful bone graft and control infection at the same time. To find a better method to resolve this dilemma, we prepared a novel clindamycin-reconstituted bone xenograft-composite (C-RBX-C) that comprised of crude bBMP (bovine bone morphogenetic protein), clindamycin, and cancellous bone scaffold, and investigated the morphology, biocompatibility, antibiotic release profile and osteoinductive potential of this composite. The ultrastructure of C-RBX-C was evaluated by scanning electron microscopy; the biocompatibility and osteoinductive potential were assessed by testing ectopic implants. The antibiotic release profile was evaluated using a disc-diffusion assay. Finally, this composite was used to repair a Staphylococcus aureus contaminated bone defect in a rabbit model. 16 weeks after the implantation of C-RBX-C, the radial defect had been completely recuperated, with significantly better formation of lamellar bone and recanalization of the marrow cavity, than in the controls (scaffolds without clindamycin or bBMP). These results demonstrate that our novel composite, with its concomitant osteoinductive and antibiotic properties, has significant potential for the treatment of contaminated or infected bone defects and osteomyelitis. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007

The study aimed to produce a novel porous gelatin-chondroitin-hyaluronate scaffold in combination with a controlled release of TGF-β1 and to evaluate its potentials in ectopic cartilage formation. The gelatin-chondroitin-hyaluronate scaffold was developed to mimic the natural extra cellular matrix of cartilage. Gelatin microspheres loaded with TGF-β1 (MS-TGFβ1) showed a fast cytokine release at initial phase (37.4%) and the ultimate accumulated release was 83.1% by day 18. Then MS-TGFβ1 were incorporated into scaffold. The MSCs seeded on scaffold with or without MS-TGFβ1 were incubated in vitro or implanted subcutaneously in nude mice. In vitro study showed that, compared to the scaffold, the scaffold/MS-TGFβ1 significantly augmented the proliferation of MSCs and GAG synthesis. Three weeks postoperatively histology observation showed that in MSCs/scaffold/MS-TGFβ1 implantation group, cells of newly formed ectopic cartilage were located within typical lacunae and demonstrated morphological characteristics of chondrocytes. Six weeks later the ectopic cartilage grew more and islands of cartilage were observed. The matrix was extensively metachromatic by safranin-O/Fast green staining. Immunohistochemical staining also indicated ectopic cartilage was intensely stained for type II collagen. Instead, in the MSCs/scaffold implantation group, no cartilage-like tissue formed and matrix showed negative or weak positive staining. The percentage of positive staining area was significantly larger in MSCs/scaffold/MS-TGFβ1 group (p<0.05) at each time point. The results indicated that the novel gelatin-chondroitin-hyaluronate scaffold with MS-TGFβ1 could induce the chondral differentiation of MSCs to form cartilage and might serve as a new way to repair cartilage defects.

The aim of the study was to produce a novel porous gelatin–chondroitin–hyaluronate scaffold in combination with a controlled release of transforming growth factor β1 (TGF‐β1), which induced the differentiation of mesenchymal stem cells (MSCs) in vivo for enhancing cartilage repair. Gelatin microspheres loaded with TGF‐β1 (MS‐TGFβ1) showed a fast release at the initial phase (37.4%), and the ultimate accumulated release was 83.1% by day 18. The autologous MSCs seeded on MS‐TGFβ1/scaffold were implanted to repair full‐thickness cartilage defects in rabbits as in vivo differentiation repair group, while MSCs differentiated in vitro were seeded on scaffold without MS‐TGFβ1 to repair the contra lateral cartilage defects (n = 30). Fifteen additional rabbits without treatment for defects were used as control. Histology observation showed that the in vivo differentiation repair group had better chondrocyte morphology, integration, continuous subchondral bone, and much thicker newly formed cartilage layer when compared to in vitro differentiation repair group 12 and 24 weeks, postoperatively. There was a significant difference in histological grading score between these two experimental groups, and both showed much better repair than that of the control. The present study implied that the novel scaffold with MS‐TGFβ1 might serve as a new way to induce the differentiation of MSCs in vivo to enhance the cartilage repair. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006

A hydroxyapatite/collagen (HAC) composite was produced to mimic the natural extracellular matrix of bone, with the collagen serving as a template for apatite formation. A three‐dimensional highly porous scaffold was developed by mixing HAC with poly(L‐lactic acid) (PLA) using a thermally induced phase separation technique. Naturally derived bovine bone morphogenetic protein (bBMP) was incorporated into the porous HAC‐PLA scaffolds, and the composite then was implanted in diaphyseal defects (2 cm in radius) of adult beagle dogs. Controls were implanted with scaffolds without BMP. The dogs were sacrificed at 6 months, at which time biocompatibility, biodegradability, and osteoinduction were evaluated by histologic and radiologic examination and by bone mineral density (BMD) measurements. All defects healed after treatment with BMP combined with HAC‐PLA, and BMD at the site of the defect was higher than the BMD of the intact radius. Fibrous union developed in the control group animals. Histologic observation indicated that the presence of BMP not only promoted osteogenesis but that it also accelerated degradation of the biomaterials. Optimized design parameters of a three‐dimensional porous biomaterial would give full scope to the role of BMP as an osteoinductive growth factor. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 591–598, 2003

To investigate the effect of anti-infective reconstituted bone xenograft as a primary graft to repair a segmental with severe contamination. A canine model of contaminated defect of 1.5 cm in size in the radius was used, in which anti-infective reconstituted bone xenograft or reconstituted bone xenograft was implanted as a primary graft followed by internal fixation. The effectiveness of the two grafting materials in repairing a contaminated segmental defect was compared. The animals which had received implant of anti-infective reconstituted bone xenograft should largely healed defects 6 months after operation while the defects implanted with reconstituted bone xenograft remained unrepaired with bone infection. Besides its strong osteoinductive and osteoconductive activity, anti-infective reconstituted bone xenograft is highly antibacterial and can be used as a primary graft to repair the severely contaminated segmental defect.