Hydrophilic bone morphogenetic protein 2 (BMP2) is easily degraded and difficult to load onto hydrophobic carrier materials, which limits the application of polyester materials in bone tissue engineering. Based on soybean-lecithin as an adjuvant biosurfactant, we designed a novel cell-free-scaffold of polymer of poly(ε-caprolactone) and poly(lactide-co-glycolide)-co-polyetherimide with abundant entrapped and continuously released BMP2 for in vivo stem cell-capture and in situ osteogenic induction, avoiding the use of exogenous cells. The optimized bioactive osteo-polyester scaffold (BOPSC), i.e. SBMP-10SC, had a high BMP2 entrapment efficiency of 95.35%. Due to its higher porosity of 83.42%, higher water uptake ratio of 850%, and sustained BMP2 release with polymer degradation, BOPSCs were demonstrated to support excellent in vitro capture, proliferation, migration and osteogenic differentiation of mouse adipose derived mesenchymal stem cells (mADSCs), and performed much better than traditional BMP-10SCs with unmodified BMP2 and single polyester scaffolds (10SCs). Furthermore, in vivo capture and migration of stem cells and differentiation into osteoblasts was observed in mice implanted with BOPSCs without exogenous cells, which enabled allogeneic bone formation with a high bone mineral density and ratios of new bone volume to existing tissue volume after 6 months. The BOPSC is an advanced 3D cell-free platform with sustained BMP2 supply for in situ stem cell capture and osteoinduction in bone tissue engineering with potential for clinical translation.

Pulmonary fibrosis (PF) is a severe chronic lung disease with little effective treatment options other than lung transplantation. Adipose-derived mesenchymal stem cells (ADSCs) have been shown to exert therapeutic effects on PF, but the underlying mechanisms remain to be further elucidated. Here, we show the interaction of ADSCs and lung-originated cells at the single-cell level, using bleomycin- (BLM-) induced mice PF model and green fluorescent protein– (GFP–) labeled mouse ADSCs. The intratracheally injected ADSCs were successfully recollected with flow cytometry and, together with lung-originated cells, were subjected to single-cell RNA sequencing (scRNA-seq). The ADSC treatment drastically changed the transcriptomic profile and composition of lung cells, especially macrophages. We explored the signal pathway interactions between ADSCs and lung-originated cells, showing potentially regulative pathways including NGR, ANNEXIN, HGF, and PERIOSTIN. Our data indicate that the injected ADSCs increased the number of Trem2+ antiinflammatory lung macrophages and lowered further inflammation and fibrosis in the lung. Our work realized the direct analysis of injected ADSCs to explore its in vivo interaction with the lung environment under PF and may provide critical information for future engineering of ADSCs to achieve better therapeutic effects in PF.

Background: Idiopathic pulmonary fibrosis (IPF) is a deadly chronic interstitial lung disease with no effective treatment options other than lung transplantation. Allogeneic adipose-derived mesenchymal stem cells (ADSCs) are considered ideal as seed cells for stem cell-based therapy, and some studies illustrated the therapeutic effect of ADSCs on IPF, but the underlying mechanisms remain unclear.Methods: A single intratracheal dose of bleomycin (BLM) was administered to induce pulmonary injury/fibrosis in C57BL/6 mice, after GFP-labeled mouse ADSCs (mADSCs) were implanted intratracheally to explore their potential therapeutic effects in the inflamed/fibrotic lung microenvironment. The mADSCs were then retrieved through fluorescence-activated cell sorting and subjected to single-cell RNA sequencing (scRNA-seq).Results: Our data indicate that the single-dose intratracheal administration of mADSCs could significantly increase the life span of IPF mice by remodeling the extracellular matrix and promoting the polarization of macrophages to an anti-inflammatory phenotype. Conclusions: A single intratracheal injection of mADSCs alleviated BLM-induced pulmonary fibrosis by readjustment of the mouse lung microenvironment, which was reflected in changes of the lung C1QB+, APOE+ and TREM2+ macrophages in the mouse model.