New Murine Model of Spontaneous Autologous Tissue Engineering, Combining an Arteriovenous Pedicle with Matrix Materials

Abstract

The authors previously described a model of tissue engineering in rats that involves the insertion of a vascular pedicle and matrix material into a semirigid closed chamber, which is buried subcutaneously. The purpose of this study was to develop a comparable model in mice, which could enable genetic mutants to be used to more extensively study the mechanisms of the angiogenesis, matrix production, and cellular migration and differentiation that occur in these models. A model that involves placing a split silicone tube around blood vessels in the mouse groin was developed and was demonstrated to successfully induce the formation of new vascularized tissue. Two vessel configurations, namely, a flow-through pedicle (n = 18 for three time points) and a ligated vascular pedicle (n = 18), were compared. The suitability of chambers constructed from either polycarbonate or silicone and the effects of incorporating either Matrigel equivalent (n = 18) or poly(DL-lactic-co-glycolic acid) (n = 18) on angiogenesis and tissue production were also tested. Empty chambers, chambers with vessels only, and chambers with matrix only served as control chambers. The results demonstrated that a flow-through type of vascular pedicle, rather than a ligated pedicle, was more reliable in terms of patency, angiogenesis, and tissue production, as were silicone chambers, compared with polycarbonate chambers. Marked angiogenesis occurred with both types of extracellular matrix scaffolds, and there was evidence that native cells could migrate into and survive within the added matrix, generating a vascularized three-dimensional construct. When Matrigel was used as the matrix, the chambers filled with adipose tissue, creating a highly vascularized fat flap. In some cases, new breast-like acini and duct tissue appeared within the fat. When poly(dl-lactic-co-glycolic acid) was used, the chambers filled with granulation and fibrous tissue but no fat or breast tissue was observed. No significant amount of tissue was generated in the control chambers. Operative times were short (25 minutes), and two chambers could be inserted into each mouse. In summary, the authors have developed an in vivo murine model for studying angiogenesis and tissue-engineering applications that is technically simple and quick to establish, has a high patency rate, and is well tolerated by the animals.

Cardiac Tissue Engineering in an In Vivo Vascularized Chamber

“…23 Here the cells grow in parallel with the newly developing capillary bed to form a vascularized interconnected network of cardiac tissue. We have previously shown in both rat 21 and mouse 38 chambers that other implanted tissues and cells, such as muscle, 17 myoblasts, 17 fat, 39 pancreatic islets, 40 fetal tissue, and fibroblasts, 16 can survive with this methodology. By seeding cardiomyocytes into a chamber in the rat, we have grown a living piece of cardiac tissue with a volume of Ϸ0.2 mL and thickness up to 1983 m, which easily exceeds the dimensions expected to be supported by diffusion alone (Figure 6).…”

Angiogenic Growth Factor Synergism in a Murine Tissue Engineering Model of Angiogenesis and Adipogenesis

“…Cylindrical silicone chambers, 5 mm long, 3.35 mm internal diameter, 44 l volume (Dow-Corning Corp., Midland, MI) were placed on the right epigastric pedicle according to a method modified from Cronin and colleagues 22 ( Figure 1, a-d). The right superficial epigastric vessels were dissected free of surrounding tissue from their origin at the femoral vessels to their insertion into the groin fat pad.…”

Macrophages Play a Key Role in Angiogenesis and Adipogenesis in a Mouse Tissue Engineering Model

“…[3][4][5][6] We have developed a murine tissue engineering model that comprises a silicon chamber enclosing the superficial epigastric vascular pedicle in a Matrigel environment. The chamber has been used in several formats, closed, 7 partially closed 8 , and in a delayed seeding model. 9 We have demonstrated that new vascularized tissue forms in the chamber 7 and that an open chamber, allowing contact with surrounding tissue, improves adipogenesis.…”