Day stay surgery for anterior cruciate ligament (ACL) reconstructions is an increasingly common practice and has driven clinicians to come up with postoperative pain regimes that allow same day mobilisation and a safe and timely discharge. There is a paucity of literature surrounding the use of intraosseous (IO) ropivacaine used as a Bier's block to provide both intraoperative and postoperative analgesia in lower limb surgery. This patient blinded, pilot study randomised 15 patients undergoing ACL reconstruction to receive either IO ropivacaine 1.5 or 2.0 mg/kg; or 300 mg of ropivacaine as local infiltration (standard of care). Toxic plasma levels of ropivacaine have been defined in the literature and therefore the primary outcome for this study was arterial plasma concentration of ropivacaine as a means to determine its safety profile. Samples were taken via an arterial line at prespecified times after tourniquet deflation. Secondary outcomes that we were interested in included immediate postoperative pain scores using the visual analogue scale (VAS) and perioperative opioid equivalent consumption.Introduction
Methods
Mesenchymal stromal cells (MSCs) are widely used in clinical trials for the treatment of many bone defects. Apatite-wollastonite glass ceramic (A-W) is an osteoconductive biomaterial shown to be compatible with MSCs. This is the first study comparing the osteogenic potential of two MSC populations, heterogeneous plastic adherence MSCs (PA-MSCs) and CD271-enriched MSCs (CD271-MSCs), when cultured on A-W 3D scaffold. The paired MSC populations were assessed for their attachment, growth kinetics and ALP activity using confocal or scanning electron microscopy and the quantifications of DNA contents and p-nitrophenyl (pNP) production. While the PA-MSCs and CD271-MSCs had similar expansion and tri-lineage differentiation capacity during standard 2D culture, they showed different proliferation kinetics when seeded on the A-W scaffolds. PA-MSCs displayed a well-spread attachment with more elongated morphology compared to CD271-MSCs, signifying a different level of interaction between the cell populations and the scaffold surface. PA-MSCs also fully integrated into the scaffold surface and showed a stronger propensity for osteogenic differentiation on the A-W scaffold as indicated by higher ALP activity than CD271-MSCs. Furthermore, A-W scaffold seeded uncultured bone marrow mononuclear cells (BM-MNCs) demonstrated a higher proliferation rate and greater ALP activity compared to freshly isolated CD271-enriched BM-MNCs. Our findings suggest that enrichment of CD271-positive population is not beneficial for osteogenesis when the cells are seeded on A-W scaffold. Furthermore, unselected heterogeneous MSCs or BM-MNCs are more promising for A-W scaffold-based bone regeneration, providing novel insight with potential clinical implications in regenerative medicine for bone defects using an innovative tissue engineering approach.
