Design and testing of biological scaffolds for delivering reparative cells to target sites in the lung

Abstract

This study summarizes the development and testing of a scaffold to promote engraftment of cells in the distal lung. A fibrinogen-fibronectin-vitronectin hydrogel (FFVH) was developed and optimized with respect to its mechanical and biological properties for this application. In vitro, FFVH scaffolds promoted attachment, histiotypic growth and expression of basement membrane proteins by primary ovine lung mesenchymal cells derived from lung biopsies. In vivo testing was then performed to assess the ability of FFVHs to promote cell engraftment in the sheep lung. Treatment with autologous cells delivered using FFVH was clinically well tolerated. Cells labelled with a fluorescent dye (PKH-26) were detected at treatment sites after 1 month. Tissue mass (assessed by CT imaging) and lung perfusion (assessed by nuclear scintigraphy) were increased at emphysema test sites. Post-treatment histology demonstrated cell proliferation and increased elastin expression without scarring or collapse. No treatment-related pathology was observed at healthy control sites. FFVH scaffolds promote cell attachment, spreading and extracellular matrix expression in vitro and apparent engraftment in vivo, with evidence of trophic effects on the surrounding tissue. Scaffolds of this type may contribute to the development of cell-based therapies for patients with end-stage pulmonary diseases.

Lung-Derived Mesenchymal Stromal Cell Post-Transplantation Survival, Persistence, Paracrine Expression, and Repair of Elastase-Injured Lung

“…describe MSCs as highly replicative and clonogenic, as observed here in passaged L-MSCs, and in past studies of outgrowth-derived L-MSCs [31,32]. After 3-4 passages, CFU efficiency reached *20%-25%.…”

“…For instance, BM or adipose-derived MSCs significantly reduced injuries caused by elastase [4][5][6][7], lipopolysaccharide [8,9], sepsis [10,11], hyperoxia [12][13][14][15][16][17], and bleomycin [18][19][20][21][22]. In general, the reparative effects of MSCs were compared with control treatments such as irradiated BMMSCs, lung fibroblasts, dermal fibroblasts, or embryonic fibroblast cell lines, rather than MSCs of lung origin, which have only recently been described in mice [23][24][25][26][27], humans [28][29][30], and sheep [31,32]. Whether lung-derived MSCs (L-MSCs) are close or distant relatives of BM-MSCs with respect to in vivo identity, cellular physiology, and therapeutic potential is unclear as is the significance of their stemness in vitro [33].…”

“…In another study in mice, L-MSCs (called multipotent lung stem cells) isolated by direct sorting (Sca-1 pos , CD31 neg , CD45 neg ) were shown to protect against elastase injury through paracrine signals [25]. Two recent studies from our laboratory employing autologous L-MSCs in an ovine model of emphysema [32,35] demonstrate significant improvements in tissue mass, perfusion, and diffusion capacity when cell were delivered intrabronchially within a biological scaffold designed to improve adherence and retention of transplanted cells. These studies show that L-MSCs, like MSCs derived from outside the lung, deliver paracrine signals that are relevant to alveolar homeostasis and injury repair, but the effectiveness of L-MSCs in comparison to BM-MSCs is unknown.…”

Initial Binding and Recellularization of Decellularized Mouse Lung Scaffolds with Bone Marrow-Derived Mesenchymal Stromal Cells

“…When cultured in synthetic polymer constructs and implanted subcutaneously in nude mice or in sheep thoracic cavities, putative somatic progenitor cells isolated from adult sheep lungs increased expression of airway and alveolar epithelial markers and developed into structures resembling lung airways and parenchyma. 33 Implantation of adult sheep lung-derived MSCs cultured in synthetic fibronectin-hydrogel scaffolds into lungs of sheep with experimentally induced emphysema resulted in improved tissue mass and lung perfusion. 33,34 Murine ESCs inoculated into decellularized rat lungs apparently differentiated into cells that expressed phenotypic markers of epithelial and vascular structures.…”

“…33 Implantation of adult sheep lung-derived MSCs cultured in synthetic fibronectin-hydrogel scaffolds into lungs of sheep with experimentally induced emphysema resulted in improved tissue mass and lung perfusion. 33,34 Murine ESCs inoculated into decellularized rat lungs apparently differentiated into cells that expressed phenotypic markers of epithelial and vascular structures. 17 These studies suggest the utility of artificial scaffolds, including whole decellularized lungs, for investigation of stem and progenitor cell growth and differentiation into lung tissue.…”