Tooth loss due to periodontal disease, dental caries, trauma, or a variety of genetic disorders continues to affect most adults adversely at some time in their lives. A biological tooth substitute that could replace lost teeth would provide a vital alternative to currently available clinical treatments. To pursue this goal, we dissociated porcine third molar tooth buds into single-cell suspensions and seeded them onto biodegradable polymers. After growing in rat hosts for 20 to 30 weeks, recognizable tooth structures formed that contained dentin, odontoblasts, a well-defined pulp chamber, putative Hertwig's root sheath epithelia, putative cementoblasts, and a morphologically correct enamel organ containing fully formed enamel. Our results demonstrate the first successful generation of tooth crowns from dissociated tooth tissues that contain both dentin and enamel, and suggest the presence of epithelial and mesenchymal dental stem cells in porcine third molar tissues.

We isolated mesenchymal stem cells (MSC) from arteries (UCA), veins (UCV), and Wharton's jelly (UCWJ) of human umbilical cords (UC) and determined their relative capacities for sustained proliferation and multilineage differentiation. Individual UC components were dissected, diced into 1-2 mm(3) fragments, and aligned in explant cultures from which migrating cells were isolated using trypsinization. Preparations from 13 UCs produced 13 UCWJ, 11 UCV, and 10 UCA cultures of fibroblast-like, spindle-shaped cells negative for CD31, CD34, CD45, CD271, and HLA-class II, but positive for CD13, CD29, CD44, CD73, CD90, CD105, and HLA-class I. UCV cells exhibited a significantly higher frequency of colony-forming units fibroblasts than did UCWJ and UCA cells. Individual MSCs could be selectively differentiated into osteoblasts, chondrocytes, and adipocytes. When compared for osteogenic potential, UCWJ cells were the least effective precursors, whereas UCA-derived cells developed alkaline phosphatase activity with or without an osteogenic stimulus. UC components, especially blood vessels, could provide a promising source of MSCs with important clinical applications.

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