Abstract
Introduction: The impact of arthroscopic temperature on joint tissues is poorly understood 45 and it is not known how mesenchymal stem cells (MSCs) respond to the effects of heat 46 generated by the device during the process of arthroscopy assisted experimental cell-based 47 therapy. In the present study, we isolated and phenotypically characterized human bone 48 marrow mesenchymal stem cells (hBMMSCs) from osteoarthritis (OA) patients, and 49 evaluated the effect of arthroscopic heat on cells in suspension and pellet cultures.Methods: Primary cultures of hBMMSCs were isolated from bone marrow aspirates of OA 52 patients and cultured using DMEM supplemented with 10% FBS and characterized for their 53 stemness. hBMMSCs (1 x 106 cells) cultured as single cell suspensions or cell pellets were 54 exposed to an illuminated arthroscope for 10, 20 or 30 min. This was followed by analysis of 55 cellular proliferation and heat shock related gene expression.Results: hBMMSCs were viable and exhibited population doubling, short spindle 58 morphology, MSC related CD surface markers expression and tri-lineage differentiation into 59 adipocytes, chondrocytes and osteoblasts. Chondrogenic and osteogenic differentiation 60 increased collagen production and alkaline phosphatase activity. Exposure of hBMMSCs to 61 an illuminated arthroscope for 10, 20 or 30 min for 72 h decreased metabolic activity of the 62 cells in suspensions (63.27% at 30 min) and increased metabolic activity in cell pellets 63 (62.86% at 10 min and 68.57% at 20 min). hBMMSCs exposed to 37C, 45C and 55C for 64 120 seconds demonstrated significant upregulation of BAX, P53, Cyclin A2, Cyclin E1, TNF-α, 65 and HSP70 in cell suspensions compared to cell pellets.Conclusions: hBMMSC cell pellets are better protected from temperature alterations 68 compared to cell suspensions. Transplantation of hBMMSCs as pellets rather than as cell 69 suspensions to the cartilage defect site would therefore support their viability and may aid 70 enhanced cartilage regeneration.