ABSTRACT
Background and Objectives@#Outbred mice are widely used in toxicology, pharmacology, and fundamental biomedical research. However, there have been no reports of in vitro culture systems for spermatogonial stem cells (SSCs) derived from these mice. @*Methods@#As a step towards constructing a non-cellular niche supporting the in vitro maintenance of outbred mouse SSC self-renewal, we systematically investigated the types of integrin heterodimers that are expressed transcriptionally, translationally, and functionally in SSCs derived from Imprinting Control Region (ICR) mice. @*Results@#Among the genes encoding 25 integrin subunits, integrin α1, α5, α6, α9, αV, and αE, and integrin β1 and β5 had significantly higher transcriptional levels than the other subunits. Furthermore, at the translational level, integrin α5, α6, α9, αV, and αE, and β1 were localized on the surface of SSCs, but integrin α1 and β5 not. Moreover, significantly stronger translational expression than integrin α9 and αE was observed in integrin α5, α6, αV, and β1. SSCs showed significantly increased adhesion to fibronectin, laminin, tenascin C and vitronectin, and functional blocking of integrin α5β1, α6β1, α9β1 or αVβ1 significantly inhibited adhesion to these molecules. @*Conclusions@#We confirmed that integrin α5β1, α6β1, α9β1 and αVβ1 actively function on the surface of undifferentiated SSCs derived from outbred ICR mice.
ABSTRACT
Since bone matrix is known to contain osteoinductive substance, many studies have been carried out for its clinical applications. But there are still controversies about its regeneration effects and bone induction. This study was performed to compare the bone induction and regeneration between bone matrix particles (BMP) and demineralized bone matrix particles (DMP). About 700 mm BMP and DMP were made from long bone of adult rabbit. They were allografted into the artificial defect formed at medial surface of tibia and observed using LM and fluorescent microscopy. More fibrin networks and osteoblasts were formed in the graft groups than in control group after 3 days of graft. At one week after graft active endochondral and intramembranous ossification were taking place by osteoinduction around the DMP, whereas osteoinduction is rarely seen around the BMP. Most of regenerated trabecular bone was replaced by immature lamellar bone in DMP group, while some amount of fibrous and trabecular structures still remained in the defect in BMP group at 4 weeks after graft. More rapid bone regeneration and maturity were seen in DMP grafted group than in BMP grafted and control groups in fluorescent microscopy at each week after graft. These results suggest that demineralized bone matrix graft is more effective than that of mineralized bone matrix in regeneration of bone defect and endochondral bone formation is not necessary in osteoinduction.