Revascularization of acellular bladder grafts

The urinary bladder is a hollow organ comprised of multiple tissue layers that serve to store and void urine from the body. There are a number of conditions in which nerve damage leads to bladder dysfunction. Some of these conditions include spinal cord injury, pelvic trauma, and congenital disorders such as spina bifida. Current bladder augmentation practices consist of surgeries utilizing the patient’s intestine or bowel for reconstruction. Gastrointestinal tissue is also used to create a neobladder for some patients with muscle invasive bladder cancer after radical cystectomy. As the use of gastrointestinal tissue for bladder reconstruction is less than optimal, a large focus of the urologic research field has been on bioengineering bladder tissues. A major contributing factor to bladder perforation and contraction of bioengineered grafts is ischemia from insufficient blood supply. Vascularization is a central component to all tissue engineering and has been of significant study in many bioengineered tissues. To generate a clinically relevant model for bladder acellular matrix graft (BAMG) vascularization, we developed a dissection technique using cadaveric rats that involved keeping a larger portion of the pelvic trunk with the bladder and upstream blood vessels intact throughout a four day decellularization process. To recreate blood vessels from an autologous source, we harvested MSCs and EPCs from rat bone marrow in which co-cultures of isolated blood vessel tissue specific cells were injected intravascularly into BAMGs and examined at various time points for evidence of vessel lining in static culture conditions. Although no evidence of vessel lining was observed, this new dissection and decellularization process allowed us to successfully gain access to a relatively small bladder vasculature.