There is an age-dependent decline of pulp regeneration, due to the decline of migration, proliferation, and cell survival of resident stem cells. Trypsin is a proteolytic enzyme clinically used for tissue repair. Here, we investigated the effects of trypsin pretreatment of pulpectomized teeth prior to cell transplantation on pulp regeneration in aged dogs. The amount of regenerated pulp was significantly higher in trypsin-pretreated teeth compared to untreated teeth. Trypsin pretreatment increased the number of cells attached to the dentinal wall that differentiated into odontoblast-like cells. The trypsin receptor, PAR2, was higher in vitro expression in the periodontal ligament cells (PDLCs) from aged dogs compared to those from young. The direct effects of trypsin on aged PDLCs were increased expression of genes related to immunomodulation, cell survival, and extracellular matrix degradation. To examine the indirect effects on microenvironment, highly extracted proteins from aged cementum were identified by proteomic analyses. Western blotting demonstrated that significantly increased fibronectin was released by the trypsin treatment of aged cementum compared to young cementum. The aged cementum extract (CE) and dentin extract (DE) by trypsin treatment increased angiogenesis, neurite extension and migration activities as elicited by fibronectin. Furthermore, the DE significantly increased the mRNA expression of immunomodulatory factors and pulp markers in the aged DPSCs. These results demonstrated the effects of trypsin on the microenvironment in addition to the resident cells including PDLCs in the aged teeth. In conclusion, the potential utility of trypsin pretreatment to stimulate pulp regeneration in aged teeth and the underlying mechanisms were demonstrated.

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Mesenchymal stem cells (MSCs) have been demonstrated to be useful for cartilage tissue regeneration. Bone marrow (BM) and synovial fluid (SF) are promising sources for MSCs to be used in cartilage regeneration. In order to improve the clinical outcomes, it is recommended that prior to clinical use, the cellular properties and, specifically, their chondrogenic potential must be investigated. The purpose of this study is to compare and better understand the in vitro chondrogenic potential of equine bone marrow-derived mesenchymal stem cells (BMMSCs) and synovial fluid-derived mesenchymal stem cells (SFMSCs) populated from the same equine donor. BM- and SF-derived MSCs cultures were generated from five equine donors, and the MSCs were evaluated in vitro for their morphology, proliferation, trilineage differentiation, and immunophenotyping. Differences in their chondrogenic potentials were further evaluated quantitatively using glycosaminoglycan (GAG) content and via immunofluorescence of chondrogenic differentiation protein markers, SRY-type HMG box9, Aggrecan, and collagen II. The BMMSCs and SFMSCs were similar in cellular morphology, viability, and immunophenotype, but, varied in their chondrogenic potential, and expression of the key chondrogenic proteins. The SFMSCs exhibited a significant increase in GAG content compared to the BMMSCs (P < 0.0001) in three donors, suggesting increased levels of chondrogenesis. The expression of the key chondrogenic proteins correlated positively with the GAG content, suggesting that the differentiation process is dependent on the expression of the target proteins in these three donors. Our findings suggest that even though SFMSCs were hypothesized to be more chondrogenic relative to BMMSCs, there was considerable donor-to-donor variation in the primary cultures of MSCs which can significantly affect their downstream application.

Horses are widely used as large animal preclinical models for cartilage repair studies, and hence, there is an interest in using equine synovial fluid-derived mesenchymal stem cells (SFMSCs) in research and clinical applications. Since, we have previously reported that similar to bone marrow-derived MSCs (BMMSCs), SFMSCs may also exhibit donor-to-donor variations in their stem cell properties; the current study was carried out as a proof-of-concept study, to compare the in vivo potential of equine BMMSCs and SFMSCs in articular cartilage repair. MSCs from these two sources were isolated from the same equine donor. In vitro analyses confirmed a significant increase in COMP expression in SFMSCs at day 14. The cells were then encapsulated in neutral agarose scaffold constructs and were implanted into two mm diameter full-thickness articular cartilage defect in trochlear grooves of the rat femur. MSCs were fluorescently labeled, and one week after treatment, the knee joints were evaluated for the presence of MSCs to the injured site and at 12 weeks were evaluated macroscopically, histologically, and then by immunofluorescence for healing of the defect. The macroscopic and histological evaluations showed better healing of the articular cartilage in the MSCs' treated knee than in the control. Interestingly, SFMSC-treated knees showed a significantly higher Col II expression, suggesting the presence of hyaline cartilage in the healed defect. Data suggests that equine SFMSCs may be a viable option for treating osteochondral defects; however, their stem cell properties require prior testing before application.

The red fox (Vulpes vulpes, order Carnivora, family Canidae, tribe Vulpini) is a universally, widespread wild carnivore in the world (Statham et al., 2014). It is the largest true fox present in the Middle East and North Africa being distributed in hill areas close to human habitats and agricultural land. In Egypt, red fox can be found along the Egyptian coast, Nile Delta and Nile Valley up to Sudanese borders (Stuart & Stuart, 2017). Its spreading is somewhat related to human distribution (Osborn & Helmy, 1980). Red foxes have an important impact on human interests since they play an integral role in conservation biology (Virgós & Travaini, 2005). Red foxes have been reported as a reservoir for rabies virus and have an important role in the trans-governmental spread of rabies virus in Egypt with a possibility of spreading to neighbouring countries via uncontrolled movement of foxes across the boundaries (El-Tholoth, El-Beskawy, & Hamed, 2015). Moreover, red foxes are considered as a potential reservoir of canine distemper virus (Aničić et al., 2018). Additionally, red foxes have an economic importance in traditional fur countries, such as the Soviet Union, Mongolia and from North America (Stubbe, 1980). Modern imaging modalities, such as computed tomography (CT), enable fast non-invasive visualization of animal anatomy in live

The coronavirus disease 2019 (COVID-19) pandemic, originating from Wuhan, China, is known to cause severe acute respiratory symptoms. The occurrence of a cytokine storm in the lungs is a critical step in the disease pathogenesis, as it causes pathological lesions, pulmonary edema, and acute respiratory distress syndrome, potentially resulting in death. Currently, there is no effective treatment that targets the cytokine storm and helps regenerate the damaged tissue. Mesenchymal stem cells (MSCs) are known to act as anti-inflammatory/immunomodulatory candidates and activate endogenous regeneration. As a result, MSC therapy is a potential treatment approach for COVID-19. Intravenous injection of clinical-grade MSCs into COVID-19 patients can induce an immunomodulatory response along with improved lung function. Dental pulp stem cells (DPSCs) are considered a potential source of MSCs for immunomodulation, tissue regeneration, and clinical application. Although some current clinical trials have treated COVID-19 patients with DPSCs, this therapy has not been approved. Here, we review the potential use of DPSCs and their significance in the development of a therapy for COVID-19.

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Background Dental pulp stem cells (DPSCs) have been developed as a potential source of mesenchymal stem cells (MSCs) for regeneration of dental pulp and other tissues. However, further strategies to isolate highly functional DPSCs beyond the colony-forming methods are required. We have demonstrated the safety and efficacy of DPSCs isolated by G-CSF-induced mobilization and cultured under normoxia (mobilized DPSCs, MDPSCs) for pulp regeneration. The device for isolation of MDPSCs, however, is not cost-effective and requires a prolonged cell culture period. It is well known that MSCs cultured under hypoxic-preconditions improved MSC proliferation activity and stemness. Therefore, in this investigation, we attempted to improve the clinical utility of DPSCs by hypoxia-preconditioned DPSCs (hpDPSCs) compared with MDPSCs to improve the potential clinical utility for pulp regeneration in endodontic dentistry. Methods Colony-forming DPSCs were isolated and preconditioned with hypoxia in a stable closed cultured system and compared with MDPSCs isolated from the individual dog teeth. We examined the proliferation rate, migration potential, anti-apoptotic activity, and gene expression of the stem cell markers and angiogenic/neurotrophic factors. Trophic effects of the conditioned medium (CM) were also evaluated. In addition, the expression of immunomodulatory molecules upon stimulation with IFN-γ was investigated. The pulp regenerative potential and transplantation safety of hpDPSCs were further assessed in pulpectomized teeth in dogs by histological and immunohistochemical analyses and by chemistry of the blood and urine tests. Results hpDPSCs demonstrated higher proliferation rate and expression of a major regulator of oxygen homeostasis, HIF-1α, and a stem cell marker, CXCR-4. The direct migratory activity of hpDPSCs in response to G-CSF was significantly higher than MDPSCs. The CM of hpDPSCs stimulated neurite extension. However, there were no changes in angiogenic, migration, and anti-apoptotic activities compared with the CM of MDPSCs. The expression of immunomodulatory gene, PTGE was significantly upregulated by IFN gamma in hpDPSCs compared with MDPSCs. However, no difference in nitric oxide was observed. The regenerated pulp tissue was quantitatively and qualitatively similar in hpDPSC transplants compared with MDPSC transplants in dog teeth. There was no evidence of toxicity or adverse events of the hpDPSC transplantation. Conclusions These results demonstrated that the efficacy of hpDPSCs for pulp regeneration was identical, although hpDPSCs improved stem cell properties compared to MDPSCs, suggesting their potential clinical utility for pulp regeneration.