| Skull bone formation occurs by either a direct intramembraneous or an indirect endochondral process. Both processes involve mesenchymal cells differentiation, synthesis and mineralization of extracellular matrix. Cranial vault forms through intramembraneous ossification of the surface mesenchyme surrounding the developing brain by direct transformation of mesenchymal cells into osteoblasts. Sutures are fibrous joints where two or more cranial and/or facial bones meet and they are found only in the skull. They enable longitudinal growth of the craniofacial bones and without them skull can grow thicker but not longer. Dura mater plays an important role in morphogenesis and phenotypic maintenance of cranial sutures and calvarial bone formation. Any alteration (genetic or environmental) in tissue interactions among the brain, dura mater, suture mesenchyme, and calvarial bones will affect skull bone formation and/or premature suture obliteration (craniosynostosis). The complexity of dura mater and cranial suture roles on brain expansion, calvarial bone formation and bone healing leads to the assumption of the presence of mesenchymal stem cells within these tissues.; Neonatal dura mater and cranial suture cells were isolated, cultured and differentiated into several restricted lineages. These cells were able to undergo osteogenic, chondrogenic, and adipogenic differentiation under specific stimulation. Adult dura mater cells failed to differentiate into chondrocytes and adipocytes. Positive staining with Stro-1 antibody and flow eytometric analysis further support the existence of cells with multiple differentiation potentials within neonatal dura mater and cranial suture tissues. However, adult dura mater failed to express Stro-I antigen.; In conclusion, a subpopulation of cells with characteristics of mesenchymal stem cells exists within neonatal dura mater and cranial suture tissues, and this population decreases significantly or is absent in adult dura mater tissue. |
