The role of Wnt signaling in mesenchymal stromal cell-driven angiogenesis.

Development, growth, and remodeling of blood vessels occur through an intricate process involving cell differentiation, proliferation, and rearrangement by cell migration under the direction of various signaling pathways. Recent reports highlight that resident and exogenous mesenchymal stromal cells (MSCs) have the potential to regulate the neovascularization process through paracrine secretion of proangiogenic factors. Recent research has established that the vasculogenic potential of MSCs is regulated by several signaling pathways, including the Wnt signaling pathway, and their interplay. These findings emphasize the complex nature of the vasculogenic process and underscore the importance of understanding the underlying molecular mechanisms for the development of effective cell-based therapies in regenerative medicine. This review provides an updated briefing on the canonical and non-canonical Wnt signaling pathways and summarizes the recent reports of both in vitro and in vivo studies with the involvement of MSCs of various sources in the vasculogenic process mediated by Wnt signaling pathways. Here we outline the current understanding of the plausible role of the Wnt signaling pathway, specifically in MSC-regulated angiogenesis.

Activation of renal vascular smooth muscle TRPV4 channels by 5-hydroxytryptamine impairs kidney function in neonatal pigs.

Control of microvascular reactivity by 5-hydroxytryptamine (5-HT; serotonin) is complex and may depend on vascular bed type and 5-HT receptors. 5-HT receptors consist of seven families (5-HT1-5-HT7), with 5-HT2 predominantly mediating renal vasoconstriction. Cyclooxygenase (COX) and smooth muscle intracellular Ca2+ levels ([Ca2+]i) have been implicated in 5-HT-induced vascular reactivity. Although 5-HT receptor expression and circulating 5-HT levels are known to be dependent on postnatal age, control of neonatal renal microvascular function by 5-HT is unclear. In the present study, we demonstrate that 5-HT stimulated human TRPV4 transiently expressed in Chinese hamster ovary cells. 5-HT2A is the predominant 5-HT2 receptor subtype in freshly isolated neonatal pig renal microvascular smooth muscle cells (SMCs). HC-067047 (HC), a selective TRPV4 blocker, attenuated cation currents induced by 5-HT in the SMCs. HC also inhibited the 5-HT-induced increase in renal microvascular [Ca2+]i and constriction. Intrarenal artery infusion of 5-HT had minimal effects on systemic hemodynamics but reduced renal blood flow (RBF) and increased renal vascular resistance (RVR) in the pigs. Transdermal measurement of glomerular filtration rate (GFR) indicated that kidney infusion of 5-HT reduced GFR. HC and 5-HT2 receptor antagonist ritanserin attenuated 5-HT effects on RBF, RVR, and GFR. Moreover, the serum and urinary COX-1 and COX-2 levels in 5-HT-treated piglets were unchanged compared with the control. These data suggest that activation of renal microvascular SMC TRPV4 channels by 5-HT impairs kidney function in neonatal pigs independently of COX production.

Advances and prospects of platelet-rich plasma therapy in veterinary ophthalmology.

In the recent decades, there has been a significant uptick on the use of platelet-rich plasma (PRP) as a better alternative for ophthalmologic therapies in pathologies, primarily of the ocular surface. PRP is a class of liquid platelet concentrate containing a supra-physiological concentration of platelets in a relatively small amount of plasma. Its potential to heal various tissues has piqued interest in its therapeutic application as a biomaterial in regenerative medicine. It is currently a popular therapeutic agent in plastic surgery, cardiothoracic surgery, reconstructive surgery, and even oral and maxillofacial surgery. Based on the data from in vitro and in vivo studies, it can be concluded that PRP possesses adequate therapeutic potential in ocular pathologies, especially those involving cornea. In addition, the high concentrations of growth factors (TGF-ß, VEGF, EGF) present in the PRP accelerate the healing of the corneal epithelium. PRP has great therapeutic prospects in veterinary ophthalmology as a regenerative therapeutic modality. However, several variables are yet to be defined and standardized that can directly affect the efficacy of PRP application in different ophthalmic conditions. There is a shortage of research on the use of PRP in ocular surface defects compared to the number of studies and reports on the use of autologous and allogeneic serum eye drops. Therefore, a data-driven approach is required to generate consensus/guidelines for the preparation, characterization, and therapeutic use of PRP in veterinary ophthalmology. This review aims to inform readers of the latest research on PRP, including its preparation methods, physiological and biochemical properties, clinical applications in veterinary ophthalmology, and their safety and efficacy.

Cell-free therapy for canine osteoarthritis: current evidence and prospects.

Osteoarthritis is a progressive degenerative disease affecting joints. It is associated with structural and functional changes that cause lameness and pain in dogs. Mesenchymal stem cells (MSCs) are considered an ideal therapeutic candidate for treating inflammatory musculoskeletal conditions due to their paracrine and immunomodulatory characteristics. They are delivered intravenously or as intra-articular injections for treating canine osteoarthritis. However, ex vivo studies have confirmed that the osteoarthritic synovial fluid is cytotoxic to cultured MSCs. Therefore, intra-articular transplantation of viable MSCs should be considered counterproductive since it minimizes cellular viability. Similarly, the intravenous administration of MSCs limits the therapeutic effects on the organ of interest since most of the administered cells get trapped in the lungs. Therefore, cell-free therapeutic strategies such as conditioned media and extracellular vesicles (EVs) can potentially become the future of MSC-based therapy in managing canine osteoarthritis. It overcomes the limitations of MSC-based therapy, such as tumor differentiation, immunogenicity, and pulmonary embolization, and has advantages like low immunogenicity and off-shelf availability. In addition, they eliminate problems such as low cell survival, transmission of infections, and unpredictable behavior of the transplanted MSCs, thereby acting as a safe alternative to cell-based therapeutics. However, very limited data is available on the efficacy and safety of cell-free therapy using MSCs for managing canine osteoarthritis. Therefore, large-scale, multicentric, randomized clinical controlled trials are required to establish the therapeutic efficacy and safety of MSC-based cell-free therapy in clinical cases of canine osteoarthritis.

Induction of reactive oxygen species by mechanical stretch drives endothelin production in neonatal pig renal epithelial cells.

Vasoactive endothelin (ET) is generated by ET converting enzyme (ECE)-induced proteolytic processing of pro-molecule big ET to biologically active peptides. H2O2 has been shown to increase the expression of ECE1 via transactivation of its promoter. The present study demonstrates that H2O2 triggered ECE1-dependent ET1-3 production in neonatal pig proximal tubule (PT) epithelial cells. A uniaxial stretch of PT cells decreased catalase, increased NADPH oxidase (NOX)2 and NOX4, and increased H2O2 levels. Stretch also increased cellular ECE1, an effect reversed by EUK-134 (a synthetic superoxide dismutase/catalase mimetic), NOX inhibitor apocynin, and siRNA-mediated knockdown of NOX2 and NOX4. Short-term unilateral ureteral obstruction (UUO), an inducer of renal tubular cell stretch and oxidative stress, increased renal ET1-3 generation and vascular resistance (RVR) in neonatal pigs. Despite removing the obstruction, UUO-induced increase in RVR persisted, resulting in early acute kidney injury (AKI). ET receptor (ETR)-operated Ca2+ entry in renal microvascular smooth muscle (SM) via transient receptor potential channel 3 (TRPC3) channels reduced renal blood flow and increased RVR. Although acute reversible UUO (rUUO) did not change protein expression levels of ETR and TRPC3 in renal microvessels, inhibition of ECE1, ETR, and TRPC3 protected against renal hypoperfusion, RVR increase, and early AKI. These data suggest that mechanical stretch-driven oxyradical generation stimulates ET production in neonatal pig renal epithelial cells. ET activates renal microvascular SM TRPC3, leading to persistent vasoconstriction and reduction in renal blood flow. These mechanisms may underlie rUUO-induced renal insufficiency in infants.

Mesenchymal Stem Cells in Veterinary Regenerative Therapy: Basic Physiology and Clinical Applications.

BACKGROUND: The consistent, self-renewal capability and wide-ranged differentiation potential during specific physiologic conditions mark stem cells as a novel candidate not only for biomedical research and regenerative therapy but also as an alternative source in research related to life sciences. This vital and distinct characteristic of stem cells enables them to offer unprecedented hope in treating many diseases and disorders, which are otherwise difficult to treat. Several efforts are still being undertaken to enhance the efficiency of MSCs for better therapeutic applications. OBJECTIVE: In the recent past, several studies have been conducted regarding the isolation of stem cells from diverse sources and are being used clinically in veterinary regenerative therapy. However, to date, only a few systemic studies are available. This study provides a comprehensive analysis of the findings from basic and applied research conducted on stem cell therapeutics with particular emphasis on animals. RESULT: On the basis of their sources, stem cells can be classified as adult or embryonic stem (ES) cells. Physiologically, the ES cells have the capability to differentiate into all body cells and develop into the normal adult organism, whereas adult stem cells serve as a repair system by restoring damaged tissues of the body. The adult stem cells referred to as Mesenchymal stem cells (MSCs) can be derived from various adult body organs, whereas embryos give rise to embryonic stem cells. MSCs possess the unique property of proliferation, trans-differentiation, and secretion of important biomolecules to create a microenvironment, which is immunosuppressive and stimulates native MSCs of damaged tissue. MSCs being immunocompromised cells can be used in autologous as well as in allogenic mode. CONCLUSION: In veterinary therapeutics, MSCs equipped with engineering and pharmaceutical modifications are offered as potential candidates in the treatment of wound healing, nerve injury, bone/ligament injury, etc., and also bear a great hope for the improvement of udder health and milk production in animals.

Physiological implications of COVID-19 in reproduction: angiotensin-converting enzyme 2 a key player.

The COVID-19 outbreak, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was first identified in China, and it has quickly become a global threat to public health due to its rapid rate of transmission and fatalities. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor that mediates the entry of SARS-CoV-2 into human cells, as in the case of severe acute respiratory syndrome coronavirus (SARS-CoV). Several studies have reported that ACE2 expression is higher in Leydig, Sertoli and seminiferous ductal cells of males, as well as in ovarian follicle cells of females, suggesting possible potential pathogenicity of the coronavirus in the reproductive system. Higher ACE2 expression in the human placenta and reports of vertical transmission of SARS-CoV-2 among clinical cases have increased the relevance of further studies in this area. This review focuses on the interaction between SARS-CoV-2 and the ACE2 receptor and speculates on the mechanistic interplay in association with male and female reproductive physiology. In addition, based on the available literature, we discuss the alleged sex differences in terms of the infectivity of SARS-CoV-2, which is claimed greater among males, and further explore the physiological role of ACE2 and 17ß-oestradiol for the same.

The preclinical and clinical implications of fetal adnexa derived mesenchymal stromal cells in wound healing therapy.

Mesenchymal stromal cells (MSCs) isolated from fetal adnexa namely amniotic membrane/epithelium, amniotic fluid and umbilical cord have hogged the limelight in recent times, as a proposed alternative to MSCs from conventional sources. These cells which are identified as being in a developmentally primitive state have many advantages, the most important being the non-invasive nature of their isolation procedures, absence of ethical concerns, proliferation potential, differentiation abilities and low immunogenicity. In the present review, we are focusing on the potential preclinical and clinical applications of different cell types of fetal adnexa, in wound healing therapy. We also discuss the isolation-culture methods, cell surface marker expression, multi-lineage differentiation abilities, immune-modulatory capabilities and their homing property. Different mechanisms involved in the wound healing process and the role of stromal cells in therapeutic wound healing are highlighted. Further, we summarize the findings of the cell delivery systems in skin lesion models and paracrine functions of their secretome in the wound healing process. Overall, this holistic review outlines the research findings of fetal adnexa derived MSCs, their usefulness in wound healing therapy in human as well as in veterinary medicine.

Human Wharton's Jelly Mesenchymal Stem Cells plasticity augments scar-free skin wound healing with hair growth.

Human mesenchymal stem cells (MSCs) are a promising candidate for cell-based transplantation and regenerative medicine therapies. Thus in the present study Wharton's Jelly Mesenchymal Stem Cells (WJ-MSCs) have been derived from extra embryonic umbilical cord matrix following removal of both arteries and vein. Also, to overcome the clinical limitations posed by fetal bovine serum (FBS) supplementation because of xenogeneic origin of FBS, usual FBS cell culture supplement has been replaced with human platelet lysate (HPL). Apart from general characteristic features of bone marrow-derived MSCs, wharton jelly-derived MSCs have the ability to maintain phenotypic attributes, cell growth kinetics, cell cycle pattern, in vitro multilineage differentiation plasticity, apoptotic pattern, normal karyotype-like intrinsic mesenchymal stem cell properties in long-term in vitro cultures. Moreover, the WJ-MSCs exhibited the in vitro multilineage differentiation capacity by giving rise to differentiated cells of not only mesodermal lineage but also to the cells of ectodermal and endodermal lineage. Also, WJ-MSC did not present any aberrant cell state upon in vivo transplantation in SCID mice and in vitro soft agar assays. The immunomodulatory potential assessed by gene expression levels of immunomodulatory factors upon exposure to inflammatory cytokines in the fetal WJ-MSCs was relatively higher compared to adult bone marrow-derived MSCs. WJ-MSCs seeded on decellularized amniotic membrane scaffold transplantation on the skin injury of SCID mice model demonstrates that combination of WJ-MSCs and decellularized amniotic membrane scaffold exhibited significantly better wound-healing capabilities, having reduced scar formation with hair growth and improved biomechanical properties of regenerated skin compared to WJ-MSCs alone. Further, our experimental data indicate that indocyanin green (ICG) at optimal concentration can be resourcefully used for labeling of stem cells and in vivo tracking by near infrared fluorescence non-invasive live cell imaging of labelled transplanted cells, thus proving its utility for therapeutic applications.