title: The use of de-differentiated chondrocytes delivered by a heparin-based hydrogel to regenerate cartilage in partial-thickness defects.
abstract: Partial-thickness cartilage defects, with no subchondral bone injury, do not repair spontaneously, thus there is no clinically effective treatment for these lesions. Although the autologous chondrocyte transplantation (ACT) is one of the promising approaches for cartilage repair, it requires in vitro cell expansion to get sufficient cells, but chondrocytes lose their chondrogenic phenotype during expansion by monolayer culture, leading to de-differentiation. In this study, a heparin-based hydrogel was evaluated and optimized to induce cartilage regeneration with de-differentiated chondrocytes. First, re-differentiation of de-differentiated chondrocytes encapsulated in heparin-based hydrogels was characterized in vitro with various polymer concentrations (from 3 to 20 wt.%). Even under a normal cell culture condition (no growth factors or chondrogenic components), efficient re-differentiation of cells was observed with the optimum at 10 wt.% hydrogel, showing the complete re-differentiation within a week. Efficient re-differentiation and cartilage formation of de-differentiated cell/hydrogel construct were also confirmed in vivo by subcutaneous implantation on the back of nude mice. Finally, excellent cartilage regeneration and good integration with surrounding, similar to natural cartilage, was also observed by delivering de-differentiated chondrocytes using the heparin-based hydrogel in partial-thickness defects of rabbit knees whereas no healing was observed for the control defects. These results demonstrate that the heparin-based hydrogel is very efficient for re-differentiation of expanded chondrocytes and cartilage regeneration without using any exogenous inducing factors, thus it could serve as an injectable cell-carrier and scaffold for cartilage repair. Excellent chondrogenic nature of the heparin-based hydrogel might be associated with the hydrogel characteristic that can secure endogenous growth factors secreted from chondrocytes, which then can promote the chondrogenesis, as suggested by the detection of TGF-β1 in both in vitro and in vivo cell/hydrogel constructs.
authors.affiliation: School of Materials Science and Engineering and Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Mihye
authors.initials: M
authors.lastname: Kim
authors.forename: Se Eun
authors.initials: SE
authors.lastname: Kim
authors.forename: Seong Soo
authors.initials: SS
authors.lastname: Kang
authors.forename: Young Ha
authors.initials: YH
authors.lastname: Kim
authors.forename: Giyoong
authors.initials: G
authors.lastname: Tae
mesh_terms: D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002356:Cartilage / Q000187:drug effects / Q000473:pathology*; D054337:Cell Dedifferentiation / Q000187:drug effects* / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D016616:Cryoultramicrotomy; D055119:Elastic Modulus / Q000187:drug effects; D005269:Femur / Q000187:drug effects / Q000473:pathology; D006025:Glycosaminoglycans / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology*; D007150:Immunohistochemistry; D051379:Mice; D011817:Rabbits; D012038:Regeneration / Q000187:drug effects*; D040521:Subcutaneous Tissue / Q000187:drug effects; D034421:Sus scrofa; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D053674:Aggrecans; D024042:Collagen Type I; D024043:Collagen Type II; D006025:Glycosaminoglycans; D053773:Transforming Growth Factor beta1; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006493:Heparin