The ability to generate lung and airway epithelial cells from human pluripotent stem cells (hPSCs) would have applications in regenerative medicine, drug screening and modeling of lung disease, and studies of human lung development. We established, based on developmental paradigms, a highly efficient method for directed differentiation of hPSCs into lung and airway epithelial cells. Long-term differentiation in vivo and in vitro yielded basal, goblet, Clara, ciliated, type I and type II alveolar epithelial cells. Type II alveolar epithelial cells generated were capable of surfactant protein-B uptake and stimulated surfactant release, providing evidence of specific function. Inhibiting or removing agonists to signaling pathways critical for early lung development in the mouse—retinoic acid, Wnt and BMP—recapitulated defects in corresponding genetic mouse knockouts. The capability of this protocol to generate most cell types of the respiratory system suggests its utility for deriving patient-specific therapeutic cells.

Background The only definitive treatment for end-stage organ failure is orthotopic transplantation. Lung extracellular matrix (ECM) holds great potential as a scaffold for lung tissue engineering since it retains the complex architecture, biomechanics and topological specificity of the lung. Decellularization of human lungs rejected from transplantation could provide “ideal” biological scaffolds for lung tissue engineering, but the availability of such lungs remains limited. The present study was designed to determine whether porcine lung could serve as a suitable substitute of human lung to study tissue-engineering therapies. Methods Human and porcine lungs were procured, sliced into sheets, and decellularized using three different methods. Compositional, ultrastructural, and biomechanical changes to the ECM were characterized. The suitability of LECM for cellular re-population was evaluated by assessing the viability, growth, and metabolic activity of human lung fibroblasts (hMRC-5s), human small airway epithelial cells (hSAECs), and human adipose-derived mesenchymal stem cells (hMSCs) over a period of seven days. Results Decellularization using CHAPS, 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate, showed the best maintenance of both human and porcine LECM, with similar retention of ECM proteins, except for elastin. Human and porcine LECM supported the cultivation of pulmonary cells in a similar way, except that the human LECM was stiffer and resulted in higher metabolic activity of the cells than porcine LECM. Conclusions Porcine lungs can be decellularized using CHAPS to produce lung ECM scaffolds with properties resembling those of human lungs, for pulmonary tissue engineering. We propose that porcine lung ECM can be an excellent screening platform for the envisioned human tissue engineering applications of decellularized lungs.

Our goal was to assess the ability of native heart extracellular matrix (ECM) to direct cardiac differentiation of human embryonic stem cells (hESCs) in vitro. In order to probe the effects of cardiac matrix on hESC differentiation, a series of hydrogels was prepared from decellularized ECM from porcine hearts by mixing ECM and collagen type I at varying ratios. Maturation of cardiac function in embryoid bodies formed from hESCs was documented in terms of spontaneous contractile behavior and the mRNA and protein expression of cardiac markers. Hydrogel with high ECM content (75% ECM, 25% collagen, no supplemental soluble factors) increased the fraction of cells expressing cardiac marker troponin T, when compared with either hydrogel with low ECM content (25% ECM, 75% collagen, no supplemental soluble factors) or collagen hydrogel (100% collagen, with supplemental soluble factors). Furthermore, cardiac maturation was promoted in high-ECM content hydrogels, as evidenced by the striation patterns of cardiac troponin I and by upregulation of Cx43 gene. Consistently, high-ECM content hydrogels improved the contractile function of cardiac cells, as evidenced by increased numbers of contracting cells and increased contraction amplitudes. The ability of native ECM hydrogel to induce cardiac differentiation of hESCs without the addition of soluble factors makes it an attractive biomaterial system for basic studies of cardiac development and potentially for the delivery of therapeutic cells into the heart.

Native extracellular matrix (ECM) that is secreted and maintained by resident cells is of great interest for cell culture and cell delivery. We hypothesized that specialized bioengineered niches for stem cells can be established using ECM-derived scaffolding materials. Kidney was selected as a model system because of the high regional diversification of renal tissue matrix. By preparing the ECM from three specialized regions of the kidney (cortex, medulla, and papilla; whole kidney, heart, and bladder as controls) in three forms: (i) intact sheets of decellularized ECM, (ii) ECM hydrogels, and (iii) solubilized ECM, we investigated how the structure and composition of ECM affect the function of kidney stem cells (with mesenchymal stem cells, MSCs, as controls). All three forms of the ECM regulated KSC function, with differential structural and compositional effects. KSCs cultured on papilla ECM consistently displayed lower proliferation, higher metabolic activity, and differences in cell morphology, alignment, and structure formation as compared to KSCs on cortex and medulla ECM, effects not observed in corresponding MSC cultures. These data suggest that tissue- and region-specific ECM can provide an effective substrate for in vitro studies of therapeutic stem cells.

Objective To assess whether equity exists in access to renal transplantation in the UK after adjustment for case mix in incident patients with end stage renal disease. Design Longitudinal cohort study. Setting UK Renal Registry and UK Transplant Registry. Participants All incident renal replacement treatment patients (n=16 202) from 65 renal centres submitting data