Use of autologous tissue is ideal in breast reconstruction; however, insufficient donor tissue and surgical and donor-site morbidity all limit its use. Tissue engineering could provide replacement tissue, but only if vascularization of large tissue volumes is achievable. The authors sought to upscale their small-animal adipose tissue-engineering models to produce large volumes of tissue in a large animal (i.e., pig).
Bilateral large-volume (78.5 ml) chambers were inserted subcutaneously in the groin enclosing a fat flap (5 ml) based on the superficial circumflex iliac pedicle for 6 (n = 4), 12 (n = 1), and 22 weeks (n = 2). Right chambers included a poly(L-lactide-co-glycolide) sponge. Other pedicle configurations, including a vascular pedicle alone (n = 2) or in combination with muscle (n = 2) or a free fat graft (n = 2), were investigated in preliminary studies. Serial assessment of tissue growth and vascularization by magnetic resonance imaging was undertaken during growth and correlated with quantitative histomorphometry at chamber removal.
All chambers filled with new tissue by 6 weeks, vascularized by the arteriovenous pedicle. In the fat flap chambers, the initial 5 ml of fat expanded to 25.9 ± 2.4, 39.4 ± 3.9, and 56.5 ml (by magnetic resonance imaging) at 6, 12, and 22 weeks, respectively. Adipose tissue volume was maintained up to 22 weeks after chamber removal (n = 2), including one where the specimen was transferred on its pedicle to an adjacent submammary pocket.
The first clinically relevant volumes of tissue for in situ and remote breast reconstruction have been formed with implications for scaling of existing tissue-engineering models into human trials.