Abstract
Introduction
Problematic bone defects are encountered regularly in orthopaedic practice particularly in fracture non-union, revision hip and knee arthroplasty, following bone tumour excision and in spinal fusion surgery. At present the optimal source of graft to ‘fill’ these defects is autologous bone but this has significant drawbacks including harvest site morbidity and limited quantities.
Bone marrow has been proposed as the main source of osteogenic stem cells for the tissue-engineered cell therapy approach to bone defect management. Such cells constitute a minute proportion of the total marrow cell population and their isolation and expansion is a time consuming and expensive strategy.
In this study we investigated human bone marrow stem cells as a potential treatment of bone defect by looking at variability in patient osteogenic cell populations as a function of patient differences. We produced a model to predict which patients would be more suited to cell based therapies and propose possible methods for improving the quality of grafts.
Methods
Bone marrow was harvested from 30 patients undergoing elective total hip replacement surgery in Musgrave Park Hospital, Belfast (12 males, 18 females, age range 52-82 years). The osteogenic stem cell fraction was cultured and subsequently analysed using colony forming efficiency assays, flow cytometry, fluorescence activated cell sorting and proteomics.
Results
The number and proliferative capacity of osteogenic stem cells varied markedly between patients. Statistical analysis revealed significantly better osteogenic capacity in:
male patients
samples in which the growth hormone Fibroblastic Growth Factor-2 was added to culture medium
patients who used the cholesterol lowering agent simvastatin
Patient use of inhaled steroids and NSAIDs were found to have detrimental effects. A statistical model to predict marrow profiles based on these variables was produced.
Conclusions
Stem cell based tissue engineering represents the future of the treatment of bone defect. This study provides evidence that inter-patient variability in marrow cell colony forming and proliferation ability can in some way be explained by patient associated factors. Using this knowledge, we can identify which patients would be best suited to this method of treatment and propose techniques for enhancement of their graft profiles.
