Engineering biomimetic 3D printed urethral tissue constructs using elastin-based bioinks for urethroplasty

Project Summary
Urethral defects requiring urethroplasty occur in children and adults secondary to congenital, traumatic,
infectious, and malignant conditions. Current tissue sources for urethral replacement are limited by donor site
morbidity and lack of optimal tissue characteristics to support lifelong voiding and penile erections. A subsequent
high risk of short- and long-term urethroplasty complications highlights the need for an improved tissue
alternative with a bioinspired design. The goal of this proposal is to engineer highly elastic, biomimetic,
three dimensional (3D) bioprinted multi-layered urethral tissue constructs by combining novel bioinks,
made of a human protein and decellularized matrix, with an innovative 3D bioprinting strategy. This
research plan addresses key design requirements: 1) achieving target elasticity by layer in a suturable construct,
2) incorporating critical biological cues to enhance wound healing and vascularization, and 3) applying a 3D
bioprinting technique to create optimized properties by layer with a recapitulation of the native urethral layered
structure. Our overall hypothesis is that these novel 3D bioprinted constructs made from methacrylate human
recombinant tropoelastin (MeTro), a photocrosslinkable human-based elastomeric hydrogel, and bladder
decellularized matrix (BAM), that are designed to meet targeted mechanical and 3D structural parameters will
improve suturability, early urinary tract function, and local tissue regeneration as compared to unseeded scaffold
urethroplasties. In Aim 1, MeTro and BAM bioinks with mechanical and structural properties that mimic native
urethral tissue will be engineered. Then, the designed bioinks will be 3D bioprinted to form cell-laden bi-layered
patch constructs containing two primary lower urinary tract cell lines: urothelium and smooth muscle cells. In
Aim 2, the in vivo efficacy of the engineered cell-laden MeTro/BAM bioprinted constructs, in seeded and
unseeded configurations, will be applied to a rat patch urethroplasty model, investigating biologic and functional
outcome parameters. Put together, this research strategy will engineer finely tuned elastic 3D printed biomimetic
constructs with target mechanical and 3D structural parameters derived from urethral tissue analyses to
maximize future clinical translatability.

Grant Number: 5R21EB035280-02
NIH Institute/Center: NIH
Principal Investigator: Nasim Annabi