Conventional allograft therapy for corneal scarring is widespread and successful, but donor tissue is not universally available, and some grafts fail owing to rejection and complications such as endothelial failure. We investigated direct treatment of corneal scarring using autologous stem cells, a therapy that, if successful, could reduce the need for corneal grafts. Mesenchymal cells were expanded from small superficial, clinically replicable limbal biopsies of human cadaveric corneo-scleral rims. Limbal biopsy–derived stromal cells (LBSCs) expanded rapidly in media containing human serum, were highly clonogenic, and could generate spheres expressing stem cell genes (ABCG2, Nestin, NGFR, Oct4, PAX6, and Sox2). Human LBSCs differentiated into keratocytes expressing characteristic marker genes (ALDH3A1, AQP1, KERA, and PTGDS) and organized a thick lamellar stroma-like tissue containing aligned collagen and keratan sulfate proteoglycans when cultured on aligned nanofiber substrata. When engrafted into mouse corneal wounds, LBSCs prevented formation of light-scattering scar tissue containing fibrotic matrix components. The presence of LBSCs induced regeneration of ablated stroma with tissue exhibiting lamellar structure and collagen organization indistinguishable from that of native tissue. Because the limbus can be easily biopsied from either eye of an affected individual and LBSCs capable of corneal stromal remodeling can be expanded under xeno-free autologous conditions, these cells present a potential for autologous stem cell–based treatment of corneal stromal blindness.

The temporomandibular joint is critical for jaw movements and allows for mastication, digestion of food, and speech. Temporomandibular joint osteoarthritis is a degenerative disease that is marked by permanent cartilage destruction and loss of extracellular matrix (ECM). To understand how the ECM regulates mandibular condylar chondrocyte (MCC) differentiation and function, we used a genetic mouse model of temporomandibular joint osteoarthritis that is deficient in two ECM proteins, biglycan and fibromodulin (Bgn Fmod؊/؊ ). Given the unavailability of cell lines, we first isolated primary MCCs and found that they were phenotypically unique from hyaline articular chondrocytes isolated from the knee joint. Using Bgn Fmod؊/؊ MCCs, we discovered the early basis for temporomandibular joint osteoarthritis arises from abnormal and accelerated chondrogenesis. Transforming growth factor (TGF)-␤1 is a growth factor that is critical for chondrogenesis and binds to both biglycan and fibromodulin. Our studies revealed the sequestration of TGF-␤1 was decreased within the ECM of Bgn ؊/0 Fmod ؊/؊ MCCs, leading to overactive TGF-␤1 signal transduction. Using an explant culture system, we found that overactive TGF-␤1 signals induced chondrogenesis and ECM turnover in this model. We demonstrated for the first time a comprehensive study revealing the importance of the ECM in maintaining the mandibular condylar cartilage integrity and identified biglycan and fibromodulin as novel key players in regulating chondrogenesis and ECM turnover during temoporomandibular joint osteoarthritis pathology.

Corneal blindness afflicts millions of individuals worldwide and is currently treated by grafting with cadaveric tissues; however, there are worldwide donor tissue shortages, and many allogeneic grafts are eventually rejected. Autologous stem cells present a prospect for personalized regenerative medicine and an alternative to cadaveric tissue grafts. Dental pulp contains a population of adult stem cells and, similar to corneal stroma, develops embryonically from the cranial neural crest. We report that adult dental pulp cells (DPCs) isolated from third molars have the capability to differentiate into keratocytes, cells of the corneal stoma. After inducing differentiation in vitro, DPCs expressed molecules characteristic of keratocytes, keratocan, and keratan sulfate proteoglycans at both the gene and the protein levels. DPCs cultured on aligned nanofiber substrates generated tissue-engineered, corneal stromal-like constructs, recapitulating the tightly packed, aligned, parallel fibrillar collagen of native stromal tissue. After injection in vivo into mouse corneal stroma, human DPCs produced corneal stromal extracellular matrix containing human type I collagen and keratocan and did not affect corneal transparency or induce immunological rejection. These findings demonstrate a potential for the clinical application of DPCs in cellular or tissue engineering therapies for corneal stromal blindness.

We describe the ectopic ossification (EO) found in tendons of biglycan (Bgn), fibromodulin (Fmod) single and double Bgn/Fmod deficient (DKO) mice with aging. At 3 months, Fmod KO, Bgn KO and DKO displayed torn cruciate ligaments and EO in their quadriceps tendon, menisci and cruciate and patellar ligaments. The phenotype was the least severe in the Fmod KO, intermediate in the Bgn KO and the most severe in the DKO. This condition progressed with age in all 3 mouse strains and resulted in the development of large supernumerary sesmoid bones. To determine the role of exercise on the extent of EO, we subjected normal and DKO mice to treadmill exercise for 3 days a week for 4 weeks. The EO in moderately exercised DKO was decreased compared to unexercised DKO mice. Finally, DKO and Bgn KO mice tested using a rotarod showed they had a reduced ability to maintain their grip on a rotating cylinder compared to WT controls. In summary, we show: 1) a detailed description of EO formed by Bgn, Fmod or combined depletion, 2) the role of exercise in modulating EO, and 3) that Bgn and Fmod are critical in controlling motor function.