This study investigates how mesenchymal stem cell's (MSCs) proliferation and migration abilities are influenced by various platelet products (PP). Donor‐matched, clinical‐, and control laboratory‐standard PPs were generated and assessed based on their platelet and leukocyte concentrations. Bone marrow derived MSCs were exposed to these PP to quantify their effect on in vitro MSC proliferation and migration. An adapted colony forming unit fibroblast (CFU‐F) assay was carried out on bone marrow aspirate using clinical‐standard PP‐loaded electrospun poly(ϵ‐caprolactone) (PCL) membrane to mimic future clinical applications to contain bone defects. Clinical‐standard PP had lower platelet (2.5 fold, p < 0.0001) and higher leukocyte (14.1 fold, p < 0.0001) concentrations compared to laboratory‐standard PP. It induced suboptimal MSC proliferation compared to laboratory‐standard PP and fetal calf serum (FCS). All PP induced significantly more MSC migration than FCS up to 24 h. The removal of leukocytes from PP had no effect on MSC proliferation or migration. The PP‐loaded membranes successfully supported MSC colony formation. This study indicates that platelet concentrations in PP impact MSC proliferation more than the presence of leukocytes, whilst MSC migration in response to PP is not influenced by platelet or leukocyte numbers. Clinical‐standard PP could be applied alongside manufactured membranes in the future treatment of bone reconstruction. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1329–1338, 2019.

Barrier membranes are popularly used for guided bone regeneration (GBR). However, more knowledge is needed to assess how these membranes could be of therapeutic value when populated with native multipotent stromal cells (MSCs), particularly in the orthopaedic field. The present manuscript investigated the activities of human bone marrow-multipotent stromal cells (BM-MSCs) when loaded on two differently structured pure collagen membranes. A crosslinked collagen membrane (CS) was tested versus a non-crosslinked bilayer collagen membrane, Bio-Gide ® (BG). Following loading with BM aspirate containing native MSCs, cell attachment to the membranes was examined using electron microscopy and flow cytometry. Furthermore, alkaline phosphatase (ALP) expression and calcium deposition levels were investigated for these BM-aspirateloaded membranes. Culture-expanded BM-MSCs were also used to load membranes and confirm the MSC functional data. All membranes supported BM-MSC attachment. However, larger numbers of attached BM-MSCs were detected for CS as compared to BG (p = 0.0010). In osteogenic medium, ALP activity was higher for CS than BG (p = 0.0312). Total calcium deposition (not normalised to cell count) was also higher for CS than BG (p = 0.0073). Consistently, the normalised secreted vascular endothelial growth factor A (VEGF-A) levels were higher in BM-MSCs loaded on CS relative to BG (p = 0.0302). Collectively, both collagen membranes supported the osteogenic functions of BM-MSCs. However, CS was found to be overall superior, probably since it provided more BM-MSC attachment. These collagen membranes could potentially be used to improve GBR outcomes in orthopaedic applications.

The current management of critical size bone defects (CSBDs) remains challenging and requires multiple surgeries. To reduce the number of surgeries, wrapping a biodegradable fibrous membrane around the defect to contain the graft and carry biological stimulants for repair is highly desirable. Poly(ε-caprolactone) (PCL) can be utilised to realise nonwoven fibrous barrier-like structures through free surface electrospinning (FSE). Human periosteum and induced membrane (IM) samples informed the development of an FSE membrane to support platelet lysate (PL) absorption, multipotential stromal cells (MSC) growth, and the prevention of cell migration. Although thinner than IM, periosteum presented a more mature vascular system with a significantly larger blood vessel diameter. The electrospun membrane (PCL3%-E) exhibited randomly configured nanoscale fibres that were successfully customised to introduce pores of increased diameter, without compromising tensile properties. Additional to the PL absorption and release capabilities needed for MSC attraction and growth, PCL3%-E also provided a favourable surface for the proliferation and alignment of periosteum- and bone marrow derived-MSCs, whilst possessing a barrier function to cell migration. These results demonstrate the development of a promising biodegradable barrier membrane enabling PL release and MSC colonisation, two key functionalities needed for the in situ formation of a transitional periosteum-like structure, enabling movement towards single-surgery CSBD reconstruction.