RESUMO
The objective of this study was to determine the effect of neurotrophin-secreting Schwann cell implants on the urinary bladder after spinal cord contusion. One hour after severe spinal cord contusion at the T8 to T11 level, carbon filaments containing nonsecreting Schwann cells, brain-derived neurotrophic factor (BDNF)-secreting Schwann cells, neurotrophin-3 (NT-3)-secreting Schwann cells, or Schwann cells secreting both BDNF and NT-3 were implanted into the spinal cord. Untreated spinal cord injured (SCI) rats and noncontused rats (C) were also studied. Two months after spinal cord injury, cystometry was performed and the bladders were studied using light microscopy. SCI rats had significantly increased bladder mass, thickness, and smooth muscle mass compared to C rats. Bladder capacity of SCI rats and rats with spinal cord implants were both significantly greater than that of C rats. This preliminary study suggests that neurotrophin-secreting Schwann cell implants may lead to improved bladder structure after spinal cord injury.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Modelos Animais de Doenças , Engenharia Genética/métodos , Implantes Experimentais/normas , Neurotrofina 3/metabolismo , Células de Schwann/metabolismo , Células de Schwann/transplante , Traumatismos da Medula Espinal/complicações , Bexiga Urinaria Neurogênica/etiologia , Bexiga Urinaria Neurogênica/terapia , Animais , Carbono , Fibra de Carbono , Técnicas de Cultura de Células/métodos , Feminino , Teste de Materiais , Tamanho do Órgão , Ratos , Ratos Sprague-Dawley , Vértebras Torácicas/lesões , Bexiga Urinaria Neurogênica/patologia , UrodinâmicaRESUMO
PURPOSE: We tested the biocompatibility of nitinol, a nickel titanium alloy, and stainless steel (SS) as bladder implant materials. MATERIALS AND METHODS: Rats received a nitinol implant, an SS implant or were sham controls. Two, 3, 6 and 8 weeks following implantation 24-hour voiding behavior studies were performed to investigate bladder irritation. All animals were sacrificed 8 weeks after implantation and a sample of urine was aspirated for culture. The bladders were examined by light microscopy and scanning electron microscopy (SEM). RESULTS: No visible encrustations or infections were noted in urine. Voiding frequency in the light period 6 weeks after implantation was significantly decreased in the 2 implant groups compared with sham controls. There were no other significant differences in frequency or mean volume per void in the light or dark periods at any time point. Light microscopy demonstrated similar implant tissue effects in all groups with little or no inflammation or fibrosis. Under SEM all implants showed a brittle, amorphous coating devoid of cells. The transition between the urothelium mucosa and the rod was smoother for SS than for nitinol, suggesting an affinity of SS for mucosa. In all nitinol rods discontinuity was present between the mucosa and rod. CONCLUSIONS: Nitinol and SS do not cause more irritation than the effects of surgery alone and the 2 materials seem to be biocompatible in the bladder. Nitinol may be more inert than SS based on SEM results.