In recent years, several studies have been conducted on Muse cells mainly due to their pluripotency, high tolerance to stress, self-renewal capacity, ability to repair DNA damage and not being tumoral. Additionally, since these stem cells can be isolated from different tissues in the adult organism, obtaining them is not considered an ethical problem, providing an advantage over embryonic stem cells. Regarding their therapeutic potential, few studies have reported clinical applications in the treatment of different diseases, such as aortic aneurysm and chondral injuries in the mouse or acute myocardial infarction in the swine, rabbit, sheep and in humans. This review aims to describe the characterization of Muse cells, show their biological characteristics, explain the differences between Muse cells and mesenchymal stem cells, and present their contribution to the treatment of some diseases.

Acute-phase proteins (APPs) are biomarkers of systemic inflammation, which allow monitoring the response to surgery and post-operative complications. Ovariectomy (OVE) can be a useful model to evaluate surgical trauma and inflammation in feline species. The objective of this study was to evaluate and compare the acute-phase response (APR) after applying two different OVE techniques by measuring serum levels of serum amyloid A (SAA), haptoglobin (Hp), total serum proteins (TSPs), albumin (ALB), and paraoxonase-1 (PON-1) during the first 48 h post-surgery (hospital stay). Forty-two female cats were selected for elective spaying. The animals were randomly distributed into two groups: laparoscopic OVE (L-OVE) and midline OVE (M-OVE). Serum SAA, Hp, TSPs, ALB, and PON-1 were measured before surgery and 1, 6, 12, 24, and 48 h post-surgery. Unlike negative APPs such as PON-1 and ALB, SAA is the most sensitive positive APP for monitoring the inflammatory response in cats undergoing OVE following laparoscopic and conventional surgery. OVE performed in cats via both laparoscopic and midline techniques results in a significative increase in SAA levels, with early recovery, minor variations in serum total protein, and no significant changes in albumin, haptoglobin, or PON-1 over a 48-h period post-procedure. Based on SAA concentrations, the response to surgical trauma does not differ between surgical techniques.

The estrous cycle involves hormonal fluctuations that influence serotonin (5-HT) concentrations and immune cell activity. During the follicular phase, estrogen increases 5-HT synthesis, enhancing cellular responses to inflammation. In contrast, in the luteal phase, progesterone suppresses immune function, reducing 5-HT availability. Age-related changes in hormone concentrations can affect these processes, potentially altering cellular responses and 5-HT dynamics in the oldest females. This study hypothesizes the relationship between 5-HT and blood cells in healthy cyclic mares, considering age as an influencing factor. Understanding these interactions offers insights into reproductive health and immune regulation in equine species. The aim was to describe the interaction between 5-HT and blood cells in twenty-five healthy cyclic Spanish Purebred mares, evaluating the effect of aging. For this purpose, the mares were classified into two age groups as follows: from 4 to 9 years (n = 12 younger mares) and from 10 to 15 years (n = 13 older mares). Younger and older mares showed an opposite 5-HT trend at +5 and +16 day of cycle (d), with greater concentrations in younger mares (p < 0.05) and lower values in older mares (p < 0.05) than at −5 and 0 d. Older mares showed a lower 5-HT concentration at +5 and +16 d (p < 0.05) than younger mares. Mares of both ages showed a superimposed WBC trend, with the greatest number both at −5 and 0 d (p < 0.05). Older mares showed a lower WBC number at −5 d (p < 0.05), and lower NFS and LYMPH numbers both at +5 and +16 d (p < 0.05) than younger mares; the latter showed the lowest NFS number at +16 d, and LYMPH number at +5 and +16 d. Mares of both ages showed a similar trend for the N/L ratio. Older mares showed a lower MON number at +5 d (p < 0.05), greater PLTs at +5 and +16 d (p < 0.05) than younger mares, and a greater PLT number at −5 and 0 d than at +5 and +16 d (p < 0.05). The activity of 5-HT is regulated by its rate of synthesis, release, and metabolism according to age. Aging reduced the 5-HT concentrations and the number of WBCs, NFSs, LYMPHs, and MONs, inducing correlations among these and 5-HT in healthy young and old cyclic mares.

Osteoarthritis (OA) is the most prevalent degenerative joint disease in both humans and companion animals, causing progressive cartilage destruction for which no curative treatment currently exists. Plasma rich in growth factors (PRGF) has shown chondroprotective effects in veterinary and preclinical models, but its efficacy is limited by the viscosity of synovial fluid and rapid degradation of growth factors within the joint. This study aimed to evaluate the effect of intra-articular co-administration of PRGF and urease-powered enzymatic nanobots on serum biomarkers of inflammation, oxidative stress, and cartilage metabolism in a rabbit (Oryctolagus cuniculus) full-depth chondral defect model (approval code: CEEA 2023-VSC-PEA-0242). Forty-one New Zealand White rabbits were allocated to a Control group (PRGF alone; n = 9 evaluable) or a Nanobots group (PRGF + nanobots; n = 24 evaluable). Twelve serum biomarkers were measured at baseline and days 28, 56, and 84. The Nanobots group showed markedly elevated serum hyaluronic acid at all timepoints (p < 0.006), significantly lower type II collagen cleavage neoepitope at day 28 (p = 0.018), persistently lower ferric reducing ability of plasma (p < 0.003), and higher C-reactive protein at days 56 and 84 (p < 0.035). These results provide preliminary in vivo evidence that urease-powered nanobots produce a distinct biomarker profile when combined with PRGF in a rabbit chondral defect model, with potential translational relevance for veterinary orthopedic therapy.

The aim of this study was to determine if the changes in plasma insulin, glucose (GLU), fructosamine (FRUCT), adrenocortical hormone (ACTH), and cortisol (CORT) concentrations in mares of different ages were substantial enough to indicate the need to also establish specific reference intervals for pregnant Spanish Purebred mares with a heterogeneous body conditional score (BCS). A total of 45 mares were used in the study, which were classified according to age into 24 10 years (from 10 to 18 years). According to the BCS, mares 10 years were distinguished into three groups as follows: underweight (BCS < 4–5; n = 8), moderate (BCS = 6–7; n = 8), and overweight (BCS = 8; n = 8) (BCS < 4–5 (n = 7), BCS = 6–7 (n = 7), and BCS = 8 (n = 7)), respectively. The main results of this study were that (I) circulating insulin, GLU, FRUCT, ACTH, and CORT concentrations were altered throughout the whole duration of pregnancy in mares; that (II) aging and BCS significantly affected insulin, ACTH, and CORT changes; and that (III) ACTH-CORT significantly correlated with insulin, FRUCT, and GLU. The results may have implications for health and disease and warrant future prospective investigations on the bidirectional interaction between insulin and the hypothalamus–pituitary–adrenal (HPA) axis in equine species, affecting the GLU and FRUCT profile through the entire physiological pregnancy.