Abstract
Mesenchymal stem cell (MSC) condensation contributes to membrane ossification by enhancing their osteodifferentiation. We investigated bone regeneration in rats using the human bone marrow-derived MSC-spheroids prepared by rotation culture, without synthetic or exogenous biomaterials. Bilateral calvarial defects (8 mm) were created in nude male rats; the left-sided defects were implanted with MSC-spheroids, β-tricalcium phosphate (β-TCP) granules, or β-TCP granules + MSC-spheroids, while the right-sided defects served as internal controls. Micro-computed tomography and immunohistochemical staining for osteocalcin/osteopontin indicated formation of new, full-thickness bones at the implantation sites, but not at the control sites in the MSC-spheroid group. Raman spectroscopy revealed similarity in the spectral properties of the repaired bone and native calvarial bone. Mechanical performance of the bones in the MSC-implanted group was good (50 and 60 % those of native bones, respectively). All tests showed poor bone regeneration in the β-TCP and β-TCP + MSC-spheroid groups. Thus, significant bone regeneration was achieved with MSC-spheroid implantation into bone defects, justifying further investigation.
Highlights
Congenital and acquired cranial bone defects occur widely worldwide and are therapeutically challenging [1, 2]
We investigated bone regeneration in rats using the human bone marrow-derived Mesenchymal stem cell (MSC)-spheroids prepared by rotation culture, without synthetic or exogenous biomaterials
Bilateral calvarial defects (8 mm) were created in nude male rats; the left-sided defects were implanted with MSC-spheroids, b-tricalcium phosphate granules, or beta-tricalcium phosphate (b-TCP) granules ? MSC-spheroids, while the right-sided defects served as internal controls
Summary
Congenital and acquired cranial bone defects occur widely worldwide and are therapeutically challenging [1, 2]. Current treatment approaches include autografts, allografts, and scaffolds made of osteoconductive materials. Drawbacks of autograft transplantation are limited supply, donor-site pain, and overall morbidity, while those of allograft transplantation are host rejection, infection, disease transmission, and inflammation [3, 4]. The osteoconductive biomaterials hydroxyapatite and beta-tricalcium phosphate (b-TCP) used for synthetic ceramic bone scaffolds [5] limited by the resorption being more rapid than the new bone formation for the former and brittleness, difficulty in molding, and minimal resorption for the latter [1]. Tissue engineering techniques for bone regeneration have been developed. Mesenchymal stem cells (MSCs) can be induced to differentiate into multiple mesodermal lineages, including bone and cartilage [6]. Mesenchymal condensation, characterized by the formation of high-density cell aggregates, occurs during the early development of several tissues [7] and involves migration of the mesenchymal progenitors to the site of skeletogenesis. Culture systems that promote mesenchymal condensation are necessary to induce osteogenic differentiation in vitro, biochemical factors can efficiently induce this differentiation
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