Repair effect of photobiomodulation combined with human umbilical cord mesenchymal stem cells on rats with acute lung injury

Biomimetic scaffold-based stem cell transplantation promotes lung regeneration

Therapeutic options are limited for severe lung injury and disease as the spontaneous regeneration of functional alveolar is terminated owing to the weakness of the inherent stem cells and the dyscrasia of the niche. Umbilical cord mesenchymal-derived stem cells (UC-MSCs) have been applied to clinical trials to promote lung repair through stem cell niche restruction. However, the application of UC-MSCs is hampered by the effectiveness of cell transplantation with few cells homing to the injury sites and poor retention, survival, and proliferation in vivo. In this study, we constructed an artificial three-dimensional (3D) biomimetic scaffold-based MSCs implant to establish a beneficial regeneration niche for endogenous stem cells in situ lung regeneration. The therapeutic potential of 3D biomimetic scaffold-based MSCs implants was evaluated by 3D culture in vitro. And RNA sequencing (RNA-Seq) was mapped to explore the gene expression involved in the niche improvement. Next, a model of partial lung resection was established in rats, and the implants were implanted into the operative region. Effects of the implants on rat resected lung injury repair were detected. The results revealed that UC-MSCs loaded on biomimetic scaffolds exerted strong paracrine effects and some UC-MSCs migrated to the lung from scaffolds and had long-term retention to suppress inflammation and fibrosis in residual lungs and promoted vascular endothelial cells and alveolar type II epithelial cells to enter the scaffolds. Then, under the guidance of the ECM-mimicking structures of scaffolds and the stimulation of the remaining UC-MSCs, vascular and alveolar-like structures were formed in the scaffold region. Moreover, the general morphology of the operative lung was also restored. Taken together, the artificial 3D biomimetic scaffold-based MSCs implants induce in situ lung regeneration and recovery after lung destruction, providing a promising direction for tissue engineering and stem cell strategies in lung regeneration.