The periodontium contains heterogeneous mesenchymal cell populations with various differentiation potentials. The capacity of these cells for tissue formation as well as the origin of their precursors are still not entirely defined. In this study, cells originating from different periodontal tissues were cultured in vitro, and tissue formation in vivo following orthotopic re-implantation was investigated. Cells were recovered from the alveolar bone and periodontal ligament tissue of six minipigs, and cultured cells were then grown on extracted dental roots from the homologous animals by means of co-culture in vitro. Each minipig received 2 roots covered with alveolar bone cells, 2 roots covered with periodontal ligament cells, and 2 control roots (without cells) implanted into palatal bone defects. Intravital fluorochrome labeling was performed, and two minipigs were histologically examined after 2, 4, and 12 weeks in each case. Controls showed widespread resorption and ankylosis, whereas roots covered with cultured periodontal cells exhibited tissue formation in vivo. Alveolar bone cells synthesized a calcified cellular tissue resembling cellular cementum, suggesting that cells within this population might differentiate into cementoblasts when reimplanted with a dental substrate in vivo. Periodontal ligament cells exhibited no calcified tissue formation in vivo, but cells synthesized a connective tissue with orientated fiber bundles attached to both host bone and root, resembling periodontal ligament.
In a search for Coxsackie B virus-induced, insulin-dependent diabetes mellitus (IDDM) we examined sera from 166 selected patients (age 1-17 years) with recent onset of IDDM for specific neutralizing antibodies. All 166 patients investigated had a clinical history of recent infectious illness. Eighty per cent of the patients had antibodies against at least one Coxsackie B virus type. But even among the children studied with antibody titers higher than 256 only in about 44% could a recent Coxsackie B virus infection be serologically demonstrated by determining specific neutralizing IgM antibodies. This result again strengthens the notion that IDDM includes several different etiologic groups, among others possibly Coxsackie B virus infections.
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