TARGETING CDKN1A WITH UC2288 TO ENHANCE OSTEOGENESIS: MECHANISTIC INSIGHTS, DIFFERENTIATION PATHWAYS, AND BIOMATERIAL-BASED DELIVERY STRATEGIES

Abstract

p21 (CDKN1A) is a regulator of the cell cycle, involved in halting cell division, coordinating DNA repair, and contributing to both senescence and apoptosis. In addition to these functions, recent evidence indicates another role in tissue repair—particularly in bone. The aim was to investigate if UC2288-medaited suppression of p21 can increase the osteogenic capacity of mesenchymal stem cells (MSCs). While UC2288 was originally developed as an anticancer agent to induce apoptosis in malignant cells, the results demonstrate that UC2288 does not compromise cell viability at moderate concentrations, indicating its potential for safe application in this context. Furthermore, MSCs treated with UC2288 expressed higher levels of key bone markers compared to untreated controls. To delineate signaling pathways that may contribute to osteogenic differentiation beyond p21 suppression, transcriptomic analysis was performed. Genes associated with the hypoxia-inducible factor-1 (HIF-1) signaling pathway were found to be upregulated in the transcriptomic data; however, subsequent validation studies did not fully corroborate these findings. Interestingly, combined suppression of HIF-1 and p21 resulted in increased expression of osteogenic marker genes. These observations suggest a potential interaction between p21 and HIF-1 signaling in regulating osteogenesis, although further experimentation is required to confirm this relationship. In the final aim, the ability of matrix stiffness to promote transdifferentiation of chondrocytes into osteoblasts was evaluated. The results demonstrated that osteogenic transdifferentiation is highly sensitive to matrix stiffness, with only a narrow range of stiffness values supporting this process. Overall, this thesis outlines a novel strategy to enhance the osteogenic capacity of mesenchymal stem cells with strong translational potential, particularly given that the therapeutic agent investigated is already approved by the FDA. Future studies will focus on in vivo validation to determine optimal dosing and treatment duration for improving bone healing following injury. Additional investigations will also assess the efficacy of this approach in pathological conditions such as advanced age, osteoporosis, and diabetes.