Cerebral-Organoid-Derived Exosomes Alleviate Oxidative Stress and Promote LMX1A-Dependent Dopaminergic Differentiation

The remarkable advancements related to cerebral organoids have provided unprecedented opportunities to model human brain development and diseases. However, despite their potential significance in neurodegenerative diseases such as Parkinson's disease (PD), the role of exosomes from cerebral organoids (OExo) has been largely unknown. In this study, we compared the effects of OExo to those of mesenchymal stem cell (MSC)-derived exosomes (CExo) and found that OExo shared similar neuroprotective effects to CExo. Our findings showed that OExo mitigated H₂O₂-induced oxidative stress and apoptosis in rat midbrain astrocytes by reducing excess ROS production, antioxidant depletion, lipid peroxidation, mitochondrial dysfunction, and the expression of pro-apoptotic genes. Notably, OExo demonstrated superiority over CExo in promoting the differentiation of human-induced pluripotent stem cells (iPSCs) into dopaminergic (DA) neurons. This was attributed to the higher abundance of neurotrophic factors, including neurotrophin-4 (NT-4) and glial-cell-derived neurotrophic factor (GDNF), in OExo, which facilitated the iPSCs' differentiation into DA neurons in an LIM homeobox transcription factor 1 alpha (LMX1A)-dependent manner. Our study provides novel insight into the biological properties of cerebral organoids and highlights the potential of OExo in the treatment of neurodegenerative diseases such as PD.

In Situ-Formed Fibrin Hydrogel Scaffold Loaded With Human Umbilical Cord Mesenchymal Stem Cells Promotes Skin Wound Healing

Healing of full-thickness skin wounds remains a major challenge. Recently, human umbilical cord mesenchymal stem cells (hUC-MSCs) were shown to possess an extraordinary potential to promote skin repair in clinical settings. However, their low survival rate after transplantation limits their therapeutic efficiency in treating full-thickness skin wounds. Hydrogels are considered an ideal cell transplantation vector owing to their three-dimensional mesh structure, good biosafety, and biodegradation. The objective of this study was to investigate the skin wound healing effect of a fibrin hydrogel scaffold loaded with hUC-MSCs. We found that the fibrin hydrogel had a three-dimensional mesh structure and low cytotoxicity and could prolong the time of cell survival in the peri-wound area. The number of green fluorescent protein (GFP)-labeled hUC-MSCs was higher in the full-thickness skin wound of mice treated with hydrogel-hUC-MSCs than those of mice treated with cell monotherapy. In addition, the combination therapy between the hydrogel and hUC-MSCs speed up wound closure, its wound healing rate was significantly higher than those of phosphate-buffered saline (PBS) therapy, hydrogel monotherapy, and hUC-MSCs monotherapy. Furthermore, the results showed that the combination therapy between hydrogel and hUC-MSCs increased keratin 10 and keratin 14 immunofluorescence staining, and upregulated the relative gene expressions of epidermal growth factor (EGF), transforming growth factor-β1 (TGF-β1), and vascular endothelial growth factor A (VEGFA), promoting epithelial regeneration and angiogenesis. In conclusion, the fibrin hydrogel scaffold provides a relatively stable sterile environment for cell adhesion, proliferation, and migration, and prolongs cell survival at the wound site. The hydrogel-hUC-MSCs combination therapy promotes wound closure, re-epithelialization, and neovascularization. It exhibits a remarkable therapeutic effect, being more effective than the monotherapy with hUC-MSCs or hydrogel.