RESUMO
Our long-term objective is to develop methods to form, in the jaw, bioengineered replacement teeth that exhibit physical properties and functions similar to those of natural teeth. Our results show that cultured rat tooth bud cells, seeded onto biodegradable scaffolds, implanted into the jaws of adult rat hosts and grown for 12 weeks, formed small, organized, bioengineered tooth crowns, containing dentin, enamel, pulp, and periodontal ligament tissues, similar to identical cell-seeded scaffolds implanted and grown in the omentum. Radiographic, histological, and immunohistochemical analyses showed that bioengineered teeth consisted of organized dentin, enamel, and pulp tissues. This study advances practical applications for dental tissue engineering by demonstrating that bioengineered tooth tissues can be regenerated at the site of previously lost teeth, and supports the use of tissue engineering strategies in humans, to regenerate previously lost and/or missing teeth. The results presented in this report support the feasibility of bioengineered replacement tooth formation in the jaw.
Assuntos
Transplante de Células/métodos , Odontogênese/fisiologia , Engenharia Tecidual/métodos , Alicerces Teciduais , Germe de Dente/transplante , Implantes Absorvíveis , Animais , Materiais Biocompatíveis , Regeneração Óssea , Calcificação Fisiológica/fisiologia , Técnicas de Cultura de Células , Diferenciação Celular , Proteínas do Esmalte Dentário/metabolismo , Dentina/metabolismo , Mandíbula/cirurgia , Ratos , Ratos Endogâmicos Lew , Dente/citologia , Dente/crescimento & desenvolvimento , Dente/metabolismo , Dente/transplante , Germe de Dente/citologia , Germe de Dente/crescimento & desenvolvimento , Germe de Dente/metabolismo , Alvéolo Dental/cirurgiaRESUMO
The recent bioengineering of complex tooth structures from pig tooth bud tissues suggests the potential for the regeneration of mammalian dental tissues. We have improved tooth bioengineering methods by comparing the utility of cultured rat tooth bud cells obtained from three- to seven-day post-natal (dpn) rats for tooth-tissue-engineering applications. Cell-seeded biodegradable scaffolds were grown in the omenta of adult rat hosts for 12 wks, then harvested. Analyses of 12-week implant tissues demonstrated that dissociated 4-dpn rat tooth bud cells seeded for 1 hr onto PGA or PLGA scaffolds generated bioengineered tooth tissues most reliably. We conclude that tooth-tissue-engineering methods can be used to generate both pig and rat tooth tissues. Furthermore, our ability to bioengineer tooth structures from cultured tooth bud cells suggests that dental epithelial and mesenchymal stem cells can be maintained in vitro for at least 6 days.
Assuntos
Implantes Absorvíveis , Odontogênese/fisiologia , Engenharia Tecidual/métodos , Germe de Dente/crescimento & desenvolvimento , Dente/crescimento & desenvolvimento , Fatores Etários , Animais , Materiais Biocompatíveis/química , Diferenciação Celular , Ácido Láctico/química , Membranas Artificiais , Omento/cirurgia , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros/química , Ratos , Ratos Endogâmicos Lew , Células-Tronco/citologia , Células-Tronco/fisiologia , Dente/citologia , Dente/transplante , Germe de Dente/citologia , Germe de Dente/transplanteRESUMO
Some infants with congenital diaphragmatic hernia who die after surgical correction have a transient postoperative period during which systemic oxygenation is adequate (honeymoon period), whereas others have persistent hypoxemia. Using morphometric techniques, we analyzed lung structure, especially the arterial bed, in seven infants who died within 1 week of surgical repair. Three infants comprised the honeymoon group, the PaO2 transiently being greater than 150 mm Hg in the descending aorta (FiO2 1.0); four infants comprised the no-honeymoon group and never had PaO2 greater than 85 mm Hg. All lungs were hypoplastic for age; with one exception, infants in the no-honeymoon group had smaller lungs. Arterial structure in the no-honeymoon group contributed to a greater reduction in pulmonary arterial cross-sectional area. Each infant in the no-honeymoon group had muscularization of intra-acinar arteries and failure of perinatal increase in compliance of small preacinar arteries, features not seen in the honeymoon group or in the normal newborn infant. In addition, compared with the honeymoon group, luminal area of preacinar and intra-acinar arteries in the no-honeymoon group was decreased by reduced external diameter or increased medial thickness. Clinical deterioration in the honeymoon group is based on a vasoconstrictive response of the hypoplastic vascular bed. Persistent hypoxemia in the no-honeymoon group is based on both severity of pulmonary hypoplasia and structural remodeling of the pulmonary arteries.