Stem Cells Develop Into Mineralized Tissues



A study published in the Journal of Clinical Periodontology characterized the mineralized tissue formed constitutively in the supracalvarial region of severe combined immunodeficiency (SCID) mice by a primitive stem cell population (human oral mucosa stem cells [hOMSC]) derived from the lamina propria of the human oral mucosa and gingiva.
Fibrin-hOMSC constructs were cultured for 14 days, then were analyzed for the expression of osteoblastic/cementoblastic markers and implanted between the skin and calvaria bones into SCID mice. After 8 weeks, the animals were sacrificed and the implantation sites analyzed. The study found that 2-week-old cultures of fibrin-hOMSC constructs expressed osteogenic/cementogenic markers at the gene level. Macroscopic and radiographic examinations revealed mineralized masses at the implantation sites of fibrin-hOMSC constructs. Histology, histochemistry, and immunofluorescence showed mineralized masses consisting of avascular cellular and acellular matrices that stained positively for collagen, calcium, cementum attachment protein, cementum protein 1, bone sialoprotein, alkaline phosphatase, osteocalcin, amelogenin and ameloblastin. Positive antihuman nuclear antigen indicated the human origin of the cells. Atomic force microscopy depicted long prismatic structures organized in lamellar aggregates.
The authors conclude that within the limitation of this study, the results indicate for the first time that fibrin-hOMSC constructs are endowed with the constitutive capacity to develop into mineralized tissues that exhibit certain similarities to cementum and bone.

(Source: Journal of Clinical Periodontology, manuscript accepted online September 11, 2012)