Dental Pulp Stem Cell-Derived Extracellular Vesicles Mitigate Haematopoietic Damage after Radiation

The proliferative effects of stem cells from apical papilla-conditioned medium on rat corneal endothelial cells

The cornea, positioned at the forefront of the eye, refracts the light for focusing images on the retina. Damage to this transparent structure can lead to various visual disorders. The corneal endothelial cells (CECs) are crucial for transparency and homeostasis, but lack the ability to reproduce. Significant damage results in structure destruction and vision impairment. While extensive research has aimed at the restoring the corneal endothelial layer, including endothelial proliferation for functional monolayers remains challenging. Our previous studies confirmed the proliferative activity of stem cells from apical papilla-conditioned medium (SCAP-CM) on the retinal pigmented epithelium as a single cell layer. This study investigates how SCAP-CM influences the proliferation and migration of CECs. Our results introduced Matrigel, as a new matrix component for in vitro culture of CECs. Moreover, 60% of SCAP-CM was able to stimulate CEC proliferation as well as migrate to repair wound healing during 24 h. Confluent CECs also expressed specific markers, ATP1a1, ZO-1 and CD56, indicative of CEC characteristics, aligning with the recapitulation of differentiation when forming a homogenous monolayer at the same level of isolated CECs without in vitro culture. These findings suggested that SCAP-CM administration could be useful for future preclinical and clinical applications.

Clinical usage of dental stem cells and their derived extracellular vesicles

Stem cell-based therapies remain at the forefront of tissue engineering and regenerative medicine because stem cells are a unique cell source with enormous potential to treat incurable diseases and even extend lifespans. The search for the best stem cell candidates continues to evolve and in recent years, dental stem cells have received significant attention due to their easy accessibility, high plasticity, and multipotential properties. Dental stem cells have been the subject of extensive research in both animal models and human clinical trials over the past two decades, and have demonstrated significant potential in ocular therapy, bone tissue engineering, and, of course, therapeutic applications in dentistry such as regenerative endodontics and periodontal tissue regeneration. These new sources of cells may be advantageous for cellular therapy and the advancement of regenerative medicine strategies, such as allogeneic transplantation or therapy with extracellular vesicles (EVs), which are functional nanoscale membrane vesicles produced by cells. This chapter discusses the accumulating research findings on cell-based regenerative therapy utilizing dental stem cells and their derived EVs, which could be a viable tool for the treatment of a variety of diseases and hence extremely valuable to mankind in the long run.

The Applications and Potentials of Extracellular Vesicles from Different Cell Sources in Periodontal Regeneration

Periodontitis is a chronic infectious disease worldwide that can cause damage to periodontal supporting tissues including gingiva, bone, cementum and periodontal ligament (PDL). The principle for the treatment of periodontitis is to control the inflammatory process. Achieving structural and functional regeneration of periodontal tissues is also essential and remains a major challenge. Though many technologies, products, and ingredients were applied in periodontal regeneration, most of the strategies have limited outcomes. Extracellular vesicles (EVs) are membranous particles with a lipid structure secreted by cells, containing a large number of biomolecules for the communication between cells. Numerous studies have demonstrated the beneficial effects of stem cell-derived EVs (SCEVs) and immune cell-derived EVs (ICEVs) on periodontal regeneration, which may be an alternative strategy for cell-based periodontal regeneration. The production of EVs is highly conserved among humans, bacteria and plants. In addition to eukaryocyte-derived EVs (CEVs), a growing body of literature suggests that bacterial/plant-derived EVs (BEVs/PEVs) also play an important role in periodontal homeostasis and regeneration. The purpose of this review is to introduce and summarize the potential therapeutic values of BEVs, CEVs and PEVs in periodontal regeneration, and discuss the current challenges and prospects for EV-based periodontal regeneration.

Current Perspectives on Adult Mesenchymal Stromal Cell-Derived Extracellular Vesicles: Biological Features and Clinical Indications

Extracellular vesicles (EVs) constitute one of the main mechanisms by which cells communicate with the surrounding tissue or at distance. Vesicle secretion is featured by most cell types, and adult mesenchymal stromal cells (MSCs) of different tissue origins have shown the ability to produce them. In recent years, several reports disclosed the molecular composition and suggested clinical indications for EVs derived from adult MSCs. The parental cells were already known for their roles in different disease settings in regulating inflammation, immune modulation, or transdifferentiation to promote cell repopulation. Interestingly, most reports also suggested that part of the properties of parental cells were maintained by isolated EV populations. This review analyzes the recent development in the field of cell-free therapies, focusing on several adult tissues as a source of MSC-derived EVs and the available clinical data from in vivo models.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for Therapeutic Use and in Bioengineering Applications

Extracellular vesicles (EVs) are small lipid bilayer-delimited particles that are naturally released from cells into body fluids, and therefore can travel and convey regulatory functions in the distal parts of the body. EVs can transmit paracrine signaling by carrying over cytokines, chemokines, growth factors, interleukins (ILs), transcription factors, and nucleic acids such as DNA, mRNAs, microRNAs, piRNAs, lncRNAs, sn/snoRNAs, mtRNAs and circRNAs; these EVs travel to predecided destinations to perform their functions. While mesenchymal stem cells (MSCs) have been shown to improve healing and facilitate treatments of various diseases, the allogenic use of these cells is often accompanied by serious adverse effects after transplantation. MSC-produced EVs are less immunogenic and can serve as an alternative to cellular therapies by transmitting signaling or delivering biomaterials to diseased areas of the body. This review article is focused on understanding the properties of EVs derived from different types of MSCs and MSC-EV-based therapeutic options. The potential of modern technologies such as 3D bioprinting to advance EV-based therapies is also discussed.

Emerging roles of extracellular vesicles in normal and malignant hematopoiesis

Hematopoietic stem cells, regulated by their microenvironment (or “niche”), sustain the production of mature blood and immune cells. Leukemia cells remodel the microenvironment to enhance their survival, which is accompanied by the loss of support for normal hematopoiesis in hematologic malignancies. Extracellular vesicles (EVs) mediate intercellular communication in physiological and pathological conditions, and deciphering their functions in cell-cell interactions in the ecosystem can highlight potential therapeutic targets. In this Review, we illustrate the utility of EVs derived from various cell types, focusing on the biological molecules they contain and the behavioral alterations they can induce in recipient cells. We also discuss the potential for clinical application in hematologic malignancies, including EV-based therapeutic regimens, drug delivery via EVs, and the use of EVs (or their cargoes) as biomarkers.

Potential neuroprotective effect of stem cells from apical papilla derived extracellular vesicles enriched by lab-on-chip approach during retinal degeneration

Retinal degeneration (RD) is recognized as a frequent cause of visual impairments, including inherited (Retinitis pigmentosa) and degenerative (age-related macular) eye diseases. Dental stem cells (DSCs) have recently demonstrated a promising neuroprotection potential for ocular diseases through a paracrine manner carried out by extracellular vesicles (EVs). However, effective isolation of EVs is still challenging, and isolation methods determine the composition of enriched EVs and the subsequent biological and functional effects. In the present study, we assessed two enrichment methods (micro-electromechanical systems and ultrafiltration) to isolate the EVs from stem cells from apical papilla (SCAP). The size distribution of the corresponding isolates exhibited the capability of each method to enrich different subsets of EVs, which significantly impacts their biological and functional effects. We confirmed the neuroprotection and anti-inflammatory capacity of the SCAP-EVs in vitro. Further experiments revealed the possible therapeutic effects of subretinal injection of SCAP-EVs in the Royal College of Surgeons (RCS) rat model. We found that EVs enriched by the micro-electromechanical-based device (MEMS-EVs) preserved visual function, reduced retinal cell apoptosis, and prevented thinning of the outer nuclear layer (ONL). Interestingly, the effect of MEMS-EVs was extended to the retinal ganglion cell/retinal nerve fiber layer (GCL/RNFL). This study supports the use of the microfluidics approach to enrich valuable subsets of EVs, together with the choice of SCAP as a source to derive EVs for cell-free therapy of RD.

Exosomes are involved in total body irradiation-induced intestinal injury in mice

Ionizing radiation-induced intestinal injury is a catastrophic complication in patients receiving radiotherapy. Circulating exosomes from patients undergoing radiotherapy can mediate communication between cells and facilitate a variety of pathological processes in vivo, but its effects on ionizing radiation-induced intestinal damage are undetermined. In this study we investigated the roles of exosomes during total body irradiation (TBI)-induced intestinal injury in vivo and in vitro. We isolated exosomes from serum of donor mice 24 h after lethal dose (9 Gy) TBI (Exo-IR-24h), then intravenously injected the exosomes into receipt mice, and found that Exo-IR-24h injection not only exacerbated 9 Gy TBI-induced lethality and weight loss, but also promoted crypt-villus structural and functional injury of the small intestine in receipt mice. Moreover, Exo-IR-24h injection significantly enhanced the apoptosis and DNA damage of small intestine in receipt mice following TBI exposure. In murine intestinal epithelial MODE-K cells, treatment with Exo-IR-24h significantly promoted 4 Gy ionizing radiation-induced apoptosis, resulting in decreased cell vitality. We further demonstrated that Exo-IR-24h promoted the IR-induced injury in receipt mice partially through its DNA damage-promoting effects and attenuating Nrf2 antioxidant response in irradiated MODE-K cells. In addition, TBI-related miRNAs and their targets in the exosomes of mice were enriched functionally using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Finally, injection of GW4869 (an inhibitor of exosome biogenesis and release, 1.25 mg·kg-1·d-1, ip, for 5 consecutive days starting 3 days before radiation exposure) was able to rescue mice against 9 Gy TBI-induced lethality and intestinal damage. Collectively, this study reveals that exosomes are involved in TBI-induced intestinal injury in mice and provides a new target to protect patients against irradiation-induced intestinal injury during radiotherapy.

HGF-Modified Dental Pulp Stem Cells Mitigate the Inflammatory and Fibrotic Responses in Paraquat-Induced Acute Respiratory Distress Syndrome

Paraquat (PQ) poisoning can cause acute lung injury and progress to pulmonary fibrosis and eventually death without effective therapy. Mesenchymal stem cells (MSCs) and hepatocyte growth factor (HGF) have been shown to partially reverse this damage. MSCs can be derived from bone marrow (BM-MSCs), adipose tissue (AD-MSCs), umbilical cord (UC-MSCs), dental pulp (DPSCs), and other sources. The biological characteristics of MSCs are specific to the tissue source. To develop an effective treatment for PQ poisoning, we compared the anti-inflammatory and antifibrotic effects of UC-MSCs and DPSCs and chose and modified a suitable source with HGF to investigate their therapeutic effects in vitro and in vivo. In this study, MSCs' supernatant was beneficial to the viability and proliferation of human lung epithelial cell BEAS-2B. Inflammatory and fibrosis-related cytokines were analyzed by real-time PCR. The results showed that MSCs' supernatant could suppress the expression of proinflammatory and profibrotic cytokines and increase the expression of anti-inflammatory and antifibrotic cytokines in BEAS-2B cells and human pulmonary fibroblast MRC-5. Extracellular vesicles (EVs) derived from MSCs performed more effectively than MSCs' supernatant. The effect of DPSCs was stronger than that of UC-MSCs and was further strengthened by HGF modification. PQ-poisoned mice were established, and UC-MSCs, DPSCs, and DPSCs-HGF were administered. Histopathological assessments revealed that DPSCs-HGF mitigated lung inflammation and collagen accumulation more effectively than the other treatments. DPSCs-HGF reduced lung permeability and increased the survival rate of PQ mice from 20% to 50%. Taken together, these results indicated that DPSCs can suppress inflammation and fibrosis in human lung cells better than UC-MSCs. The anti-inflammatory and antifibrotic effects were significantly enhanced by HGF modification. DPSCs-HGF ameliorated pulmonitis and pulmonary fibrosis in PQ mice, effectively improving the survival rate, which might be mediated by paracrine mechanisms. The results suggested that DPSCs-HGF transplantation was a potential therapeutic approach for PQ poisoning.