Lung Regeneration by Transplantation of Allogeneic Lung Progenitors Using a Safer Conditioning Regimen and Clinical-grade Reagents

Over the last decades, several studies demonstrated the possibility of lung regeneration through transplantation of various lung progenitor populations. Recently, we showed in mice that fetal or adult lung progenitors could potentially provide donor cells for transplantation, provided that the lung stem cell niche in the recipient is vacated of endogenous lung progenitors by adequate conditioning. Accordingly, marked lung regeneration could be attained following i.v. infusion of a single cell suspension of lung cells into recipient mice conditioned with naphthalene (NA) and 6Gy total body irradiation (TBI). As clinical translation of this approach requires the use of allogenic donors, we more recently developed a novel transplantation modality based on co-infusion of hematopoietic and lung progenitors from the same donor. Thus, by virtue of hematopoietic chimerism, which leads to immune tolerance toward donor antigens, the lung progenitors can be successfully engrafted without any need for post-transplant immune suppression. In the present study, we demonstrate that it is possible to replace NA in the conditioning regimen with Cyclophosphamide (CY), approved for the treatment of many diseases and that a lower dose of 2 GY TBI can successfully enable engraftment of donor-derived hematopoietic and lung progenitors when CY is administered in 2 doses after the stem cell infusion. Taken together, our results suggest a feasible and relatively safe protocol that could potentially be translated to clinical transplantation of lung progenitors across major MHC barriers in patients with terminal lung diseases.

Lung Injury Repair by Transplantation of Adult Lung Cells Following Preconditioning of Recipient Mice

Repair of injured lungs represents a longstanding therapeutic challenge. We recently demonstrated that human and mouse embryonic lung tissue from the canalicular stage of development are enriched with lung progenitors, and that a single cell suspension of canalicular lungs can be used for transplantation, provided that lung progenitor niches in the recipient mice are vacated by strategies similar to those used in bone marrow transplantation. Considering the ethical limitations associated with the use of fetal cells, we investigated here whether adult lungs could offer an alternative source of lung progenitors for transplantation. We show that intravenous infusion of a single cell suspension of adult mouse lungs from GFP+ donors, following conditioning of recipient mice with naphthalene and subsequent sublethal irradiation, led to marked colonization of the recipient lungs, at 6-8 weeks post-transplant, with donor derived structures including epithelial, endothelial, and mesenchymal cells. Epithelial cells within these donor-derived colonies expressed markers of functionally distinct lung cell types, and lung function, which is significantly compromised in mice treated with naphthalene and radiation, was found to be corrected following transplantation. Dose response analysis suggests that the frequency of patch forming cells in adult lungs was about threefold lower compared to that found in E16 fetal lungs. However, as adult lungs are much larger, the total number of patch forming cells that can be collected from this source is significantly greater. Our study provides proof of concept for lung regeneration by adult lung cells after preconditioning to vacate the pulmonary niche. Stem Cells Translational Medicine 2018;7:68-77.

The proteomic profile of hereditary inclusion body myopathy

Hereditary inclusion body myopathy (HIBM) is an adult onset, slowly progressive distal and proximal myopathy. Although the causing gene, GNE, encodes for a key enzyme in the biosynthesis of sialic acid, its primary function in HIBM remains unknown. The goal of this study was to unravel new clues on the biological pathways leading to HIBM by proteomic comparison. Muscle cultures and biopsies were analyzed by two dimensional gel electrophoresis (2-DE) and the same biopsy extracts by isobaric tag for relative and absolute quantitation (iTRAQ). Proteins that were differentially expressed in all HIBM specimens versus all controls in each analysis were identified by mass spectrometry. The muscle cultures 2-DE analysis yielded 41 such proteins, while the biopsies 2-DE analysis showed 26 differentially expressed proteins. Out of the 400 proteins identified in biopsies by iTRAQ, 41 showed altered expression. In spite of the different nature of specimens (muscle primary cultures versus muscle biopsies) and of the different methods applied (2D gels versus iTRAQ) the differentially expressed proteins identified in each of the three analyses where related mainly to the same pathways, ubiquitination, stress response and mitochondrial processes, but the most robust cluster (30%) was assigned to cytoskeleton and sarcomere organization. Taken together, these findings indicate a possible novel function of GNE in the muscle filamentous apparatus that could be involved in the pathogenesis of HIBM.