Expansion of human bone marrow stromal cells on poly-( dl-lactide- co-glycolide) (P DLLGA) hollow fibres designed for use in skeletal tissue engineering

Abstract

Strategies to expand human bone marrow stromal cells (HBMSC) for bone tissue engineering are a key to revolutionising the processes involved in three-dimensional skeletal tissue reconstruction. To facilitate this process we believe the use of biodegradable porous poly( dl-lactide- co-glycolide) (P DLLGA) hollow fibres as a scaffold used in combination with HBMSC to initiate natural bone repair and regeneration offers a potential solution. In this study, the biocompatibility of 75:25 P DLLGA fibres with HBMSC and the capacity of a P DLLGA fibre-associated HBMSC-monolayer to establish an osteogenic phenotype in vivo was examined. A high proportion of HBMSC survived when expanded on P DLLGA fibres for 6 days, with only 10% of the propidium iodide (pI)-labelled population represented in the sub-G1 DNA peak on analysis by flow cytometry. Tracking carboxy-fluorescein diacetate, succinimidyl ester (CFSE)-labelled HBMSC by flow cytometry indicated that HBMSC attachment to the P DLLGA fibres does not interfere with their rate of proliferation. Furthermore, in response to osteogenic stimuli, HBMSC expanded on P DLLGA fibres can differentiate, as expected, along the osteogenic lineage with associated alkaline phosphatase activity. Following implantation into SCID mice, osteogenic-conditioned P DLLGA fibre–HBMSC graft resulted in type I collagen deposition and associated bone mineralisation and osteoid formation, as evidenced by immunohistochemistry and histology. These studies provide evidence that porous P DLLGA hollow fibre–HBMSC graft is an innovative biomaterial that offers new approaches to mesenchymal cell expansion, which could be utilised as a scaffold for skeletal tissue generation.