RESUMEN
Hydrogel scaffolds provide a beneficial microenvironment in transected rat spinal cord. A combinatorial biomaterials-based strategy provided a microenvironment that facilitated regeneration while reducing foreign body reaction to the three-dimensional spinal cord construct. We used poly lactic-co-glycolic acid microspheres to provide sustained release of rapamycin from Schwann cell (SC)-loaded, positively charged oligo-polyethylene glycol fumarate scaffolds. The biological activity and dose-release characteristics of rapamycin from microspheres alone and from microspheres embedded in the scaffold were determined in vitro. Three dose formulations of rapamycin were compared with controls in 53 rats. We observed a dose-dependent reduction in the fibrotic reaction to the scaffold and improved functional recovery over 6 weeks. Recovery was replicated in a second cohort of 28 animals that included retransection injury. Immunohistochemical and stereological analysis demonstrated that blood vessel number, surface area, vessel diameter, basement membrane collagen, and microvessel phenotype within the regenerated tissue was dependent on the presence of SCs and rapamycin. TRITC-dextran injection demonstrated enhanced perfusion into scaffold channels. Rapamycin also increased the number of descending regenerated axons, as assessed by Fast Blue retrograde axonal tracing. These results demonstrate that normalization of the neovasculature was associated with enhanced axonal regeneration and improved function after spinal cord transection.
Asunto(s)
Células Inmovilizadas , Microesferas , Células de Schwann , Sirolimus , Regeneración de la Medula Espinal , Andamios del Tejido/química , Animales , Línea Celular , Células Inmovilizadas/metabolismo , Células Inmovilizadas/patología , Células Inmovilizadas/trasplante , Preparaciones de Acción Retardada/química , Preparaciones de Acción Retardada/farmacocinética , Preparaciones de Acción Retardada/farmacología , Femenino , Polietilenglicoles/química , Polietilenglicoles/farmacocinética , Polietilenglicoles/farmacología , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/farmacocinética , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/farmacología , Ratas , Ratas Endogámicas F344 , Células de Schwann/metabolismo , Células de Schwann/patología , Células de Schwann/trasplante , Sirolimus/química , Sirolimus/farmacocinética , Sirolimus/farmacología , Traumatismos de la Médula Espinal/metabolismo , Traumatismos de la Médula Espinal/patología , Traumatismos de la Médula Espinal/terapia , Ingeniería de TejidosRESUMEN
BACKGROUND: Although considerable evidence exists regarding margin status and reexcision for patients undergoing breast conservation therapy, few data address the impact of a close margin for patients undergoing mastectomy without postmastectomy radiotherapy. METHODS: This retrospective review identified 1147 patients who underwent 1206 mastectomies with negative final margins for breast cancer from 2006 to 2010. Margin distance was analyzed as a continuous variable and dichotomized variable ((≤2 vs >2 mm). Patients undergoing adjuvant radiation therapy were excluded from the study. Uni- and multivariable analyses were used to assess the association of reexcision, proximity of the final margin, adjuvant therapy, and other clinical and pathologic factors with local recurrence (LR). RESULTS: In 158 mastectomies (13.1%), a reexcision was performed for a close (n = 90) or positive (n = 68) margin. All but one were identified intraoperatively using frozen section analysis. The reexcision rates for skin- and nipple-sparing mastectomy (SSM/NSM) were higher than for simple mastectomy (SM) (19.8 vs 9.3%; p < 0.001). The overall 5-year risk for an LR was 3.8%. The risk was 3.1% for a margin greater than 2 mm and 11.2% for a margin of 2 mm or smaller. In the multivariable model, proximity of the final margin measured as a continuous variable was found to be a significant risk factor for LR (p = 0.009), whereas adjuvant endocrine therapy was found to be protective (p = 0.03). Intraoperative reexcision was not significant in the multivariable model (p = 0.23). CONCLUSIONS: For patients undergoing mastectomy for breast cancer, a wider final margin correlated with a reduced risk for LR. The rates for LR were similar between SSM/NSM and SM despite higher rates of intraoperative reexcision for SSM/NSM.
Asunto(s)
Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/patología , Carcinoma Intraductal no Infiltrante/patología , Mastectomía , Recurrencia Local de Neoplasia/patología , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/cirugía , Carcinoma Ductal de Mama/cirugía , Carcinoma Intraductal no Infiltrante/cirugía , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Invasividad Neoplásica , Recurrencia Local de Neoplasia/cirugía , Pronóstico , Radioterapia Adyuvante , Estudios Retrospectivos , Adulto JovenRESUMEN
In utero cell transplantation (IUCT) can lead to the postnatal engraftment of human cells in the xenogeneic recipient. Most reports of IUCT have involved hematopoietic stem cells. It is unknown whether human hepatocytes used for IUCT in fetal pigs will lead to the engraftment of these same cells in the postnatal environment. In this study, fetal pigs received direct liver injections of 1 × 10(7) human hepatocytes in utero and were delivered by cesarean section at term. The piglets received a second direct liver injection of 5 × 10(7) human hepatocytes 1 week after birth. The serum was analyzed for human albumin 2, 4, and 6 weeks after engraftment. Piglet livers were harvested 6 weeks after transplantation and were examined by immunohistochemistry, polymerase chain reaction, and fluorescence in situ hybridization for human-specific sequences. Piglets undergoing IUCT with human hepatocytes that were postnatally engrafted with human hepatocytes showed significant levels of human albumin production in their serum at all postengraftment time points. Human albumin gene expression, the presence of human hepatocytes, and the presence of human beta-2 microglobulin were all confirmed 6 weeks after engraftment. IUCT in fetal pigs with human hepatocytes early in gestation allowed the engraftment of human hepatocytes, which remained viable and functional for weeks after transplantation. IUCT followed by postnatal engraftment may provide a future means for large-scale expansion of human hepatocytes in genetically engineered pigs.