ARTHRITIC PERIOSTEAL TISSUE FROM JOINT REPLACEMENT SURGERY AS AN AUTOLOGOUS SOURCE OF STEM CELLS

Summary Statement Progenitor cells from the periosteal niche are of great clinical interest due to their remarkable regenerative capacity. Here we report on progenitor cells from arthritic patients whose femoral neck periosteum was resected over the course of hip replacement. Introduction This study aims to determine whether periosteum derived cells (PDCs) can be isolated from tissue resected in the normal course of hip arthroplasty. Further, it aims to determine how different isolation protocols affect PDC behavior (surface marker expression, proliferation, and differentiation). In addition, the study aims to characterise the populations of PDCs, isolated through either enzymatic digestion or migration, and their relative capacity to differentiate down multiple capacities; direct comparison with commercially available human marrow-derived stromal cells cultured under identical conditions will enable the placement of the PDC data in context of the current state of the field. Methods Proximal femoral head/neck explants (n=4) were acquired from patients within 8 h of hip replacement surgery (IRB 12–335, Cleveland Clinic), after examination and diagnosis by pathology. To isolate digested PDCs (dPDCS), the minced tissue is suspended in 3 mg/ml collagenase II (Gibco) solution in alpha-MEM with Glutamax (Invitrogen) with 1% antibioticantimycotic (Invitrogen) overnight in a 37°C incubator. Any undigested tissue is filtered from the cells using a 100 μm filter, and isolated cells are cultured in standard culture media. To isolate migrated PDCs (mPDCs), the minced tissue is directly plated into tissue culture flasks in alpha-MEM with Glutamax supplemented with 10% FBS (Invitrogen), 1% antibioticantimycotic overnight, and cultured in standard culture media. The cells are left to egress from the tissue for one week. Finally, validated bone marrow derived hMSCs (BMSCs) are purchased from four independent vendors (Lonza, PromoCell, ScienCell, Cell Applications) as standards for comparison. Cell cohorts are compared using proliferation assays, cell population analysis using flow cytometry, and quantitative adipogenesis, osteogenesis and chondrogenesis assays. Results PDCs and BMSCs exhibit similar proliferation rate, morphology, and surface receptor expression. PDCs showed no significant differences to BMSCs with regard to osteo- and adipogenic differentiation capacity. Chondrogenic assay of PDCs showed increased pellet size with pellets exhibiting staining indicative of hyaline cartilage for BMSC, and immature fibrocartilage for dPDCs and mPDCs. This study demonstrates, for the first time to our knowledge, the feasibility of isolating PDCs from the femoral neck of patients undergoing joint replacement surgery. PDCs and BMSCs exhibit similar surface marker expression and equivalent adipogenic and osteogenic capacity. Interestingly, cell cohorts from the same tissue albeit different isolation protocols show intrinsic differences in their differentiation capacities. Additionally, all cell types display marked intraindividual differences in their capacity to differentiate down different lineages, with no significant correlation to age. Discussion/Conclusion The femoral neck periosteum offers a feasible source for isolation and a possible source for banking of autologous multipotent cells with similar potential as BMSCs. Further in vivo studies will determine the regenerative capacity of these cells in a more physiological context.