Brian Walczak, Clinical Instructor, Orthopedics & Rehabilitation (Li Lab), “Reprogrammed Mesenchymal Stem Cells Acquire Enhanced Therapeutic Potential For Cartilage Repair”

Topic: Reprogrammed Mesenchymal Stem Cells Acquire Enhanced Therapeutic Potential For Cartilage Repair

Abstract: Mesenchymal stem cells (MSCs) hold promise as a therapeutic agent for cartilage repair, but successful clinical outcomes are highly dependent on the quality of MSCs. For example, advancing age and medical co-morbidities increase MSC senescence and reduce their differentiation. However, it has been shown that cellular reprogramming is able to erase epigenetic marks associated with aging, which in turn improves cell function and associated therapeutic properties. In this study, we aimed to demonstrate if MSCs after cellular reprogramming are able to display enhanced therapeutic properties and functions critical for cartilage repair. After approval from the Institutional Review Board (IRB), MSCs were isolated from knee synovial fluid from patients undergoing surgery who had osteoarthritis (parental MSCs), reprogrammed into induced pluripotent stem cells (iPSCs) using non-integration virus-free episomal vectors, and then differentiated into induced pluripotent stem cell-derived MSCs (reprogrammed MSCs). Our results showed significantly greater mean cumulative population doubling numbers and cell proliferation in the reprogrammed MSC group compared to parental MSC controls. Histological staining showed that chondrogenic pellets after reprogramming contained more spherical chondrocytes with increased proteoglycan content. Noticeably, COL2A1 was increased and COL10 was decreased in chondrogenic pellets after reprogramming. Similarly, GAG production and cartilage-associated markers including COL2B, only expressed in mature chondrocytes, were significantly increased in reprogrammed MSC pellets compared to parental MSCs. Reprogrammed MSC also demonstrated the ability to immunoregulate catabolic expression of chondrocyte matrix matelloproteases. Faxitron imaging following in vivo intra-articular stifle joint injection, using a guinea pig model of degenerative joint osteoarthritis, demonstrated a significant preservation of joint space, a decrease in inflammatory cytokine levels, and an increase in cartilage architecture and proteoglycan staining on histologic analysis, in animals who received reprogrammed MSC injections. In summary, our data suggest that cellular reprogramming improves cell growth characteristics, chondrogenic potential, and ability to regulate key catabolic properties in vitro . Moreover, reprogrammed MSCs are able to significantly preserved articular cartilage in vivo using an animal model of degenerative joint osteoarthritis. The clinical impact is that cellular reprogramming of MSCs obtained from patients with chondral diseases improves the cell’s therapeutic potential for subsequent cartilage repair therapies.