DelNero_wk3

It was a busy week in the OR with a spectrum of cases, literally from head to toe, including a craniotomy, double mastectomy and breast reconstructions, two abdominal wall reconstructions, a lip reconstruction, and a femoral popitial bypass surgery. The bypass surgery was particularly interesting, as it shed light on the needs and challenges of tissue engineered vessel constructs. In this case, the patient needed to replace nearly 100 cm of the femoral artery, stretching from the hip to the foot. The vascular surgeon hoped to harvest the replacement tissue from whatever he could salvage from the bad leg, as well as both arms. For many reasons, the best sources of tissue substitutes are other parts of your own body, which are satisfy the top challenges that tissue engineers face: immunological response, biocompatible and remodelable, inexpensive. Unfortunately, for the diabetic patient in question, the arteries also exemplified the biggest drawback of autologous grafts: availability. The sites that the doctor hoped to retrieve healthy vessels were not sufficient for the graft, especially in the leg where large numbers of small, corollary vessels had formed to supplement the femoral artery. Therefore, the doctor was obliged to use a synthetic alternative, essentially a plastic Gore-Tex tube, to complete the bypass. Noteably, this material lacked all of the advantages of the autologous graft, providing only a mechanically stable channel for blood flow with no hope of biological performance. Consequently, the expected outcome for the bypass dropped to just around 3 years. From my perspective as a tissue engineer, and I imagine in the opinions of the doctors and patients, this dramatic gap between human tissue and current gold-standards in peripheral bypass surgery is alarming. Even if the patient had a sufficient supply of healthy vessels, the morbidity associated with removing 100 cm of native vasculature is non-trivial. This surgery impressed upon me the urgency of developing and implementing tissue engineered solutions in the surgical toolbox.

This lesson was reinforced in the total mastectomy case, which used diep flaps from the patient’s abdomen to replace both breasts. The benefit of fully vascularized, fully biological, and non-immunological tissue replacements was obvious. In this operation, fat tissue from the waist is almost identical to the original adipose. Barring the advantage of a complementary tummy-tuck, engineering of biologically active tissue is clearly needed in plastic and reconstructive surgery. 

Meanwhile, in the lab, we are working to produce exactly these types of alternative tissue replacements by designing flap and graft scaffolds from extracellular matrix proteins. By micropatterning these materials, the lab already showed improved cellularization in mouse models. Now we are attempting to use a new method of fabrication to produce micro-scale features that facilitate angiogenesis and cellular remodeling. Perhaps this project will lead to promising alternatives for the patients we meet in the OR.