In VivoPulmonary Tissue Engineering: Contribution of Donor-Derived Endothelial Cells to Construct Vascularization*

Abstract

Intrapulmonary engraftment of engineered lung tissues could provide a potential therapeutic approach for the treatment of pediatric and adult pulmonary diseases. In working toward this goal, we report here on in vivo generation of vascularized pulmonary tissue constructs utilizing the subcutaneous Matrigel plug model. Mixed populations of murine fetal pulmonary cells (FPCs) containing epithelial, mesenchymal, and endothelial cells (ECs) were isolated from the lungs of embryonic day 17.5 fetuses. FPCs were admixed to Matrigel and injected subcutaneously into the anterior abdominal wall of adult C57/BL6 mice to facilitate in vivo pulmonary tissue construct formation. Vascularization was enhanced by placing fibroblast growth factor 2 (FGF2)-loaded polyvinyl sponges into the hydrogel. After 1 week, routine histology and immunohistochemical staining for donor-derived epithelial cells and ECs as well as analysis of patent vasculature in the constructs following tail vein injection of fluorescein isothiocyanate-conjugated dextran were performed. In the Matrigel-only controls, some level of host infiltrate, but no measurable vascularization, was detected. In the presence of FPCs, the constructs contained ductal epithelial structures and patent vasculature. In the absence of FPCs, exogenous FGF2 induced the formation of numerous patent blood vessels throughout the entire constructs; in combination with FPCs, it resulted in enhanced capillary density and abundant interfacing between developing epithelial and vascular structures. The significant findings of this study are that distal pulmonary epithelial differentiation (as assessed by the expression of prosurfactant protein C) can be maintained in vivo and that donor-derived ECs contribute to the formation of patent vessels that interface tightly with ductal epithelial structures.

EngineeringDe NovoAssembly of Fetal Pulmonary Organoids

“…[18][19][20] In these studies we used a mixed population of embryonic day 17.5 (E17.5) murine fetal pulmonary cells (FPCs) (onset of the saccular stage) cultured under serum-free conditions in 3D collagen type I hydrogels. In this setting, the use of a serum-free medium containing fibroblast growth factor (FGF)-10, -7, and -2 (FGF-10/7/2)-stimulated formation of 3D histiotypic fetal lung structures comprised of sacculated distal (proSpC-expressing) epithelial structures enrobed in and interfaced with capillary-like endothelial networks.…”

Coming to terms with tissue engineering and regenerative medicine in the lung

“…In addition to collagen, Matrigel (101,123,124) and other natural polymers (6) have been explored in both in vitro and in vivo studies. Synthetic polymers such as polyglycolic acid (175), polylactic-coglycolic acid (PLGA) (122), and pluronic F-127 are also considered of substantial interest in the context of lung scaffolds (35).…”

Computational and bioengineered lungs as alternatives to whole animal, isolated organ, and cell-based lung models

“…Natural ECM such as collagen (19,69,128,129,145), Matrigel (115,116), and other naturally occurring polymers (2) have been used for both in vitro and in vivo studies. Similarly, synthetic polymers such as polyglycolic acid (PGA) (142), poly(lacticco-glycolic acid) (PLGA) (115), and pluronic F-127 (PF-127) (34) have shown great potential for lung reconstruction.…”