Apoptotic vesicles derived from human red blood cells promote bone regeneration via carbonic anhydrase 1

Tailored apoptotic vesicles promote bone regeneration by releasing the osteoinductive brake

Accumulating evidence has demonstrated that apoptotic vesicles (apoVs) derived from mesenchymal stem cells (MSCs; MSC-apoVs) are vital for bone regeneration, and possess superior capabilities compared to MSCs and other extracellular vesicles derived from MSCs (such as exosomes). The osteoinductive effect of MSC-apoVs is attributed to their diverse contents, especially enriched proteins or microRNAs (miRNAs). To optimize their osteoinduction activity, it is necessary to determine the unique cargo profiles of MSC-apoVs. We previously established the protein landscape and identified proteins specific to MSC-apoVs. However, the features and functions of miRNAs enriched in MSC-apoVs are unclear. In this study, we compared MSCs, MSC-apoVs, and MSC-exosomes from two types of MSC. We generated a map of miRNAs specific to MSC-apoVs and identified seven miRNAs specifically enriched in MSC-apoVs compared to MSCs and MSC-exosomes, which we classified as apoV-specific miRNAs. Among these seven specific miRNAs, hsa-miR-4485-3p was the most abundant and stable. Next, we explored its function in apoV-mediated osteoinduction. Unexpectedly, hsa-miR-4485-3p enriched in MSC-apoVs inhibited osteogenesis and promoted adipogenesis by targeting the AKT pathway. Tailored apoVs with downregulated hsa-miR-4485-3p exhibited a greater effect on bone regeneration than control apoVs. Like releasing the brake, we acquired more powerful osteoinductive apoVs. In summary, we identified the miRNA cargos, including miRNAs specific to MSC-apoVs, and generated tailored apoVs with high osteoinduction activity, which is promising in apoV-based therapies for bone regeneration.

Platelet-Derived Apoptotic Vesicles Promote Bone Regeneration via Golgi Phosphoprotein 2 (GOLPH2)-AKT Signaling Axis

Apoptotic vesicles (apoVs) are apoptotic-cell-derived nanosized vesicles that take on dominant roles in regulating bone homeostasis. We have demonstrated that mesenchymal stem cell (MSC)-derived apoVs are promising therapeutic agents for bone regeneration. However, clinical translation of MSC-derived apoVs has been hindered due to cell expansion and nuclear substance. As another appealing source for apoV therapy, blood cells could potentially eliminate these limitations. However, whether blood cells can release apoVs during apoptosis is uncertain, and the detailed characteristics and biological properties of respective apoVs are not elucidated. In this study, we showed that platelets (PLTs) could rapidly release abundant apoVs during apoptosis in a short time. To recognize the different protein expressions between PLT-derived apoVs and PLTs, we established their precise protein landscape. Furthermore, we identified six proteins specifically enriched in PLT-derived apoVs, which could be considered as specific biomarkers. More importantly, PLT-derived apoVs promoted osteogenesis of MSCs and rescued bone loss via Golgi phosphoprotein 2 (GOLPH2)-induced AKT phosphorylation, therefore, leading to the emergence of their potential in bone regeneration. In summary, we comprehensively determined characteristics of PLT-derived apoVs and confirmed their roles in bone metabolism through previously unrecognized GOPLH2-dependent AKT signaling, providing more understanding for exploring apoV-based therapy in bone tissue engineering.

Extracellular Vesicles: Emergent and Multiple Sources in Wound Healing Treatment

Non-healing wound- and tissue-injury are commonly experienced worldwide by the aging population. The persistence of disease commonly leads to tissue infection, resulting in severe clinical complications. In the last decade, extracellular vesicles (EVs) have been considered promising and emergent therapeutic tools to improve the healing processes. Therefore, efforts have been directed to develop a cell-free therapeutic platform based on EV administration to orchestrate tissue repair. EVs derived from different cell types, including fibroblast, epithelial, and immune cells are recruited to the injured sites and in turn take part in scar formation. EVs are nano-sized particles containing a heterogeneous cargo consisting of lipids, proteins, and nucleic acids protected from degradation by their lipid bilayer. Noteworthy, since EVs have natural biocompatibility and low immunogenicity, they represent the ideal therapeutic candidates for regenerative purposes. Indeed, EVs are released by several cell types, and even if they possess unique biological properties, their functional capability can be further improved by engineering their content and functionalizing their surface, allowing a specific cell cargo delivery. Herein, we provide an overview of preclinical data supporting the contribution of EVs in the repair and regenerative processes, focusing on different naïve EV sources, as well as on their engineering, to offer a scalable and low-cost therapeutic option for tissue repair.