Abstract
BackgroundThe use of mesenchymal stem cells (MSCs) and coralline hydroxyapatite (HA) or biphasic calcium phosphate (BCP) as a bone substitute for posterolateral spinal fusion has been reported. However, the genes and molecular signals by which MSCs interact with their surrounding environment require further elucidation.MethodsMSCs were harvested from bone grafting patients and identified by flow cytometry. A composite scaffold was developed using poly(lactide-co-glycolide) (PLGA) copolymer, coralline HA, BCP, and collagen as a carrier matrix for MSCs. The gene expression profiles of MSCs cultured in the scaffolds were measured by microarrays. The alkaline phosphatase (ALP) activity of the MSCs was assessed, and the expression of osteogenic genes and proteins was determined by quantitative polymerase chain reaction (Q-PCR) and Western blotting. Furthermore, we cultured rabbit MSCs in BCP or coralline HA hybrid scaffolds and transplanted these mixtures into rabbits for spinal fusion. We investigated the differences between BCP and coralline HA hybrid scaffolds by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT).ResultsTested in vitro, the cells were negative for hematopoietic cell markers and positive for MSC markers. There was higher expression of 80 genes and lower of 101 genes of MSCs cultured in BCP hybrid scaffolds. Some of these genes have been shown to play a role in osteogenesis of MSCs. In addition, MSCs cultured in BCP hybrid scaffolds produced more messenger RNA (mRNA) for osteopontin, osteocalcin, Runx2, and leptin receptor (leptin-R) than those cultured in coralline HA hybrid scaffolds. Western blotting showed more Runx2 and leptin-R protein expression in BCP hybrid scaffolds. For in vivo results, 3D reconstructed CT images showed continuous bone bridges and fusion mass incorporated with the transverse processes. Bone mineral content (BMC) values were higher in the BCP hybrid scaffold group than in the coralline HA hybrid scaffold group.ConclusionsThe BCP hybrid scaffold for osteogenesis of MSCs is better than the coralline HA hybrid scaffold by upregulating expression of leptin-R. This was consistent with in vivo data, which indicated that BCP hybrid scaffolds induced more bone formation in a spinal fusion model.
Highlights
Autogenous bone is the most effective graft material for the repair of bone defects or for spinal fusion; donor site morbidity is a major limitation on its clinical use [1]
We investigated the differences between biphasic calcium phosphate (BCP) and HA hybrid scaffolds by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT) examination
Gene expression profiling mesenchymal stem cells (MSCs) cultured in different scaffolds modulate the expression of several genes, leading to higher expression of 80 genes (BCP hybrid scaffold/coralline HA hybrid scaffold ratio >1.5-fold) and lower expression of 101 genes (BCP hybrid scaffold/coralline HA hybrid scaffold ratio
Summary
Autogenous bone is the most effective graft material for the repair of bone defects or for spinal fusion; donor site morbidity is a major limitation on its clinical use [1]. To avoid this limitation, one tissue engineering approach would be to combine cells capable of osteogenic activity with an appropriate scaffolding material to stimulate bone regeneration and repair. The molecular and biochemical signals by which MSCs interact with their surrounding environment require further elucidation to develop improved scaffolding materials. The use of mesenchymal stem cells (MSCs) and coralline hydroxyapatite (HA) or biphasic calcium phosphate (BCP) as a bone substitute for posterolateral spinal fusion has been reported. The genes and molecular signals by which MSCs interact with their surrounding environment require further elucidation
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