Posterolateral spinal fusion with nano-hydroxyapatite-collagen/PLA composite and autologous adipose-derived mesenchymal stem cells in a rabbit model

Spinal fusion is routinely performed to treat low back pain caused by degeneration of intervertebral discs. An autologous bone graft derived from the iliac crest is the standard procedure used for spinal fusion. However, several shortcomings, including pseudarthrosis, pain and the need for blood transfusion are known to be associated with the procedure. Our study analysed the effectiveness of a new mineralized collagen matrix, nano-hydroxyapatitecollagenpolylactic acid (nHACPLA), combined with autologous adipose-derived mesenchymal stem cells (ADMSCs) as a graft material for posterolateral spinal fusion in a rabbit model. Forty rabbits were randomly divided into four groups: autologous iliac crest bone group (ACB), nHACPLA composite group (nHACPLA), autologous iliac crest bone mixed with nHACPLA composite group (ACB + nHACPLA), and nHACPLA composite combined with ADMSCs (ADMSCs + nHACPLA). The viability and the proliferation of the ADMSCs seeded on the scaffolds were evaluated by live/dead kit and MTT assay in vitro, respectively. Lumbar posterolateral fusions were assessed by manual palpation, radiographical and histological procedures, mechanical strength and scanning electronic microscopy (SEM) in 10 weeks of observation. The results showed that the rate of fusion was significantly higher in the ACB and ADMSCs + nHACPLA groups than that in the nHACPLA and ACB + nHACPLA groups. It was not significantly higher in the ACB group than in the ADMSCs + nHACPLA group. From microstructural analysis of the samples using histological staining methods, there was more new bone-like tissue formation in the ACB and ADMSCs + nHACPLA groups than that in the other two groups at the 10th postoperative week. Our study demonstrated the effective impact of nHACPLA combined with ADMSCs in rabbit posterolateral spinal fusion. Copyright (c) 2011 John Wiley & Sons, Ltd.