Comparison of cell populations in tissue samples of the acetabulum and proximal femur of patients with hip osteoarthritis

Introduction

During hip replacement surgery, bone marrow (BM) containing tissues accumulate as residual products representing potential sources of progenitor cells for regenerative therapies. Therefore, we characterized BM mononuclear cells (BMNC) from the acetabulum and proximal femur of patients with hip osteoarthritis.

Material and Methods

BMNC were isolated from tissue samples of 18 predominantly elderly (mean age 64 years), overweight (BMI-average 30 kg/m²) patients (56% female). BM mesenchymal stromal cells (BMSC), immune and hematopoietic cells were analyzed by flow cytometry. Besides the ability of BMSC for osteogenic and adipogenic differentiation, colony forming capacities of BMSC and hematopoietic progenitors were determined. Cell-population characteristics were compared between donor-matched acetabular and femoral samples.

Results

BMNC density in acetabular samples was nine times lower compared to femoral samples. While there was little difference in the frequency of native BMSC-markers in flow cytometry, tissue progenitor cells from acetabulum exhibited significantly shorter generation doubling times, better colony formation and stronger mineralization in osteogenic differentiation than cells from femur. Despite a much lower CD45⁺ population and plasma cell fraction (CD19⁺CD38⁺CD138⁺), significantly higher proportions of T cells (CD45⁺CD3⁺), especially T-helper cells (CD45⁺CD3⁺CD4⁺(CD25⁺)), were found in acetabular samples. In contrast, hematopoietic (CD34⁺) and clonogenic erythroid progenitor cells were increased in femoral samples associated with higher lipid droplet accumulation in adipogenic differentiation assays of BMSC.

Conclusion

Acetabular samples revealed a pro-inflammatory cell-population with activated T-helper cells and increased capacity for osteogenic mineralization, whereas femoral samples contained increased cells of the hematopoietic developmental lineage. Whether these differences are due to the influence of osteoarthritis or the different anatomical-functional origin should be clarified in further investigations.

Acknowledgements

This work was supported by the Interdisciplinary Center for Clinical Research (IZKF) at the University Hospital of Wuerzburg (Project D-361). J.H. was supported by the grant (MD Excellence Program) from the Faculty of Medicine and the Graduate School of Life Sciences, University of Wuerzburg.

Conflict of Interest

Authors declare no competing interests.

Publication History

Article published online:
04 November 2021