Osteopontin expression in healing wounds of horses and in human keloids

The critical role of osteopontin (OPN) in fibrotic diseases

Fibrosis is a pathological condition characterized by the excessive deposition of extracellular matrix components in tissues and organs, leading to progressive architectural remodelling and contributing to the development of various diseases. Osteopontin (OPN), a highly phosphorylated glycoprotein, has been increasingly recognized for its involvement in the progression of tissue fibrosis. This review provides a comprehensive overview of the genetic and protein structure of OPN and focuses on our current understanding of the role of OPN in the development of fibrosis in the lungs and other tissues. Additionally, special attention is given to the potential of OPN as a biomarker and a novel therapeutic target in the treatment of fibrosis.

Advances in the pathogenesis and clinical application prospects of tumor biomolecules in keloid

Keloid scarring is a kind of pathological healing manifestation after skin injury and possesses various tumor properties, such as the Warburg effect, epithelial-mesenchymal transition (EMT), expression imbalances of apoptosis-related genes and the presence of stem cells. Abnormal expression of tumor signatures is critical to the initiation and operation of these effects. Although previous experimental studies have recognized the potential value of a single or several tumor biomolecules in keloids, a comprehensive evaluation system for multiple tumor signatures in keloid scarring is still lacking. This paper aims to summarize tumor biomolecules in keloids from the perspectives of liquid biopsy, genetics, proteomics and epigenetics and to investigate their mechanisms of action and feasibility from bench to bedside. Liquid biopsy is suitable for the early screening of people with keloids due to its noninvasive and accurate performance. Epigenetic biomarkers do not require changes in the gene sequence and their reversibility and tissue specificity make them ideal therapeutic targets. Nonetheless, given the ethnic specificity and genetic predisposition of keloids, more large-sample multicenter studies are indispensable for determining the prevalence of these signatures and for establishing diagnostic criteria and therapeutic efficacy estimations based on these molecules.

The granulation (t)issue: A narrative and scoping review of basic and clinical research of the equine distal limb exuberant wound healing disorder

Exuberant granulation tissue (EGT) is often observed during second intention wound healing in horses. Despite its impact on wound care, the basic mechanisms leading to EGT are still unclear and effective strategies to prevent and/or treat EGT are lacking. The development of EGT is a poorly understood, multifactorial process involving hyperproliferating fibroblasts and malfunctional differentiation of keratinocytes, suboptimal wound contraction, dysfunctional vascularisation, and chronic inflammation. To consolidate and describe basic and clinical research literature on EGT and to identify knowledge gaps and opportunities for future research, a search was systematically conducted using predefined search terms. Subsequently, a scoping review was conducted using specific criteria to select the peer-reviewed literature that described methods to treat and/or prevent EGT. Proposed mechanisms of effects as well as results and main conclusions were extracted and tabulated. The systematic search resulted in 1062 publications in PubMed and 767 in Web of Science. Twenty additional studies were later included. Of these, 327 studies were reviewed for the narrative review on basic research and 35 controlled clinical trials were eligible for the scoping review. All 35 studies were conducted in university hospitals, and all but one involved surgically induced non-infected wounds. The study population was predominantly horses (n = 230) with a small number of ponies (n = 18) and donkeys (n = 14). In conclusion, there remains a strong need for evidence-based recommendations on EGT treatment, preferably using multi-centre studies that represent the general population of horses, include higher numbers of animals, and are performed in naturally occurring wounds. This narrative and scoping review also emphasises the importance of incorporating basic research knowledge in the study design of clinical trials.

The Horse as a Model for the Study of Cutaneous Wound Healing

Significance: Cutaneous wounds are a major problem in both human and equine medicine. The economic cost of treating skin wounds and related complications in humans and horses is high, and in both species, particular types of chronic wounds do not respond well to current therapies, leading to suffering and morbidity. Recent Advances: Conventional methods for the treatment of cutaneous wounds are generic and have not changed significantly in decades. However, as more is learned about the mechanisms involved in normal skin wound healing, and how failure of these processes leads to chronic nonhealing wounds, novel therapies targeting the specific pathologies of hard-to-heal wounds are being developed and evaluated. Critical Issues: Physiologically relevant animal models are needed to (1) study the mechanisms involved in normal and impaired skin wound healing and (2) test newly developed therapies. Future Directions: Similarities in normal wound healing in humans and horses, and the natural development of distinct types of hard-to-heal chronic wounds in both species, make the horse a physiologically relevant model for the study of mechanisms involved in wound repair. Horses are also well-suited models to test novel therapies. In addition, studies in horses have the potential to benefit veterinary, as well as human medicine.

Equine early pregnancy endocrine profiles and ipsilateral endometrial immune cell, gene expression and protein localisation response

We investigated the early effects of the equine embryo on maternal serum concentrations of insulin-like growth factor 1 (IGF1), leptin and adiponectin, uterine immune cells and genes and proteins related to embryo development and the maintenance of pregnancy. Ipsilateral endometrial expression was assessed on Days 7 and 13 after ovulation for the following transcripts: oestrogen receptor ERα (ESR1), progesterone receptor (PGR), progestin and adipoQ receptor family member 5 (PAQR5), oxytocin receptor (OXTR), prostaglandin-endoperoxide synthase 2 (PTGS2), raf-1 proto-oncogene serine/threonine kinase (RAF1), p21-activated kinase 6 (PAK6), fibroblast growth factor family member 9 (FGF9), IGF1 and its receptor (IGF1R), mucin 1 (MUC1), osteopontin (OPN), leptin receptor (LEPR) and adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2). Ipsilateral endometrial immunological cell infiltration and immunohistochemical protein localisation were evaluated on Days 7, 10 and 13 after ovulation for ERα, PGR, OXTR, PTGS2, IGF1, IGF1R, IGF2 and MUC1. Serum hormone concentrations were not affected by reproductive status. Pregnancy downregulated ESR1 and PGR mRNA levels, upregulated the expression of all other genes and affected the expression of all genes, except PGR, on Day 7 (compared with eight genes affected at Day 13). Proteins were affected by pregnancy or by its interaction with other variables (day of extraction and endometrial compartment). Pregnant mares had a higher lymphocyte count, which decreased towards Day 13. The effect of pregnancy on leucocytes and proteins was more evident in superficial endometrial compartments. The results of this study suggest that the equine embryo exerts prompt paracrine regulation of critical biological processes.

Leaf Extract of Aerva javanica Suppresses Excessive Growth of Granulation Tissue in Horses

Wound healing in horses is complicated by the excessive growth of granulation tissue, commonly known as proud flesh and is similar to keloids in human beings. At present, there is no satisfactory treatment for proud flesh in horses. In this study, we, for the first time, demonstrated that leaf extract of Aerva javanica suppresses excessive growth of granulation tissue in horses. Many plant flavonoids are claimed to have antiproliferative properties. Kaempferol is a natural flavonoid containing 3-hydroxy flavone backbone found in many plants in its aglycone form and attached with various sugars. Ecdysteroids are steroidal analogs of invertebrate steroidal hormones found in plants. Both flavonoids and ecdysteroids accumulate more in plants during abiotic stress. We hypothesized that Aerva javanica may have high levels of ecdysteroids and kaempferols for surviving in stressful conditions of desert. Those kaempferols may suppress the growth of granulation tissue by their antiangiogenesis property. Ecdysteroids may control the larvae of habronema if associated with proud flesh. Extract was prepared using solvent-based fractionation and silica gel column flash chromatography. Application of the leaf extract in horses suppressed growth of granulation tissue along with restoration of normal skin function. Various purification steps and mass spectrometry were used to identify the active components in the study.

Understanding Keloid Pathobiology From a Quasi-Neoplastic Perspective: Less of a Scar and More of a Chronic Inflammatory Disease With Cancer-Like Tendencies

Keloids are considered as benign fibroproliferative skin tumors growing beyond the site of the original dermal injury. Although traditionally viewed as a form of skin scarring, keloids display many cancer-like characteristics such as progressive uncontrolled growth, lack of spontaneous regression and extremely high rates of recurrence. Phenotypically, keloids are consistent with non-malignant dermal tumors that are due to the excessive overproduction of collagen which never metastasize. Within the remit of keloid pathobiology, there is increasing evidence for the various interplay of neoplastic-promoting and suppressing factors, which may explain its aggressive clinical behavior. Amongst the most compelling parallels between keloids and cancer are their shared cellular bioenergetics, epigenetic methylation profiles and epithelial-to-mesenchymal transition amongst other disease biological (genotypic and phenotypic) behaviors. This review explores the quasi-neoplastic or cancer-like properties of keloids and highlights areas for future study.

Feasibility of a disposable canister-free negative-pressure wound therapy (NPWT) device for treating open wounds in horses

BACKGROUND

Wounds are among the most common medical conditions affecting horses and have a major economic impact on the horse industry. Wound healing in horses is distinct to that documented in other species, and often results in delayed healing and extensive scarring, with compromised functional and aesthetic outcomes. To date, there is no conventional method objectively proven to accelerate healing or to successfully prevent complications associated with second intention healing. Several effects of Negative Pressure Wound Therapy (NPWT) may be particularly useful to the management of wounds in horses. However, cumbersome designs of classic NPWT devices render them unsuitable for equine practice. A new lightweight, portable and disposable unit of NPWT (PICO®), should facilitate the use of this modality by equine practitioners. The aim of this study was to evaluate the feasibility of using this canister-free system to treat experimental open wounds in horses.

RESULTS

No difficulties were encountered with the application or maintenance of the PICO® system during the ex vivo experiment or during the preliminary in vivo experiment conducted on intact skin. All horses readily tolerated the PICO® but difficulties with adhesion and seal prevented the completion of the experimental wound study despite the use of many adjunctive adhesives.

CONCLUSION

The current PICO® dressing design is not suitable to be used as a dressing for open wounds in horses though the device is well tolerated by equine patients. A dressing with a wider adhesive edge, a superior adhesive and a more flexible pad would likely be better adapted to enable its future use in equine practice.

Evaluation of Systemic and Local Inflammatory Parameters and Manifestations of Pain in an Equine Experimental Wound Model

In the last decades, a well-established equine wound model has been used to study fibroproliferative wound healing disorders. The aim of this study was to characterize the degree of discomfort of wounding and sampling in an equine excisional wound model by evaluating systemic and local inflammatory responses and signs of pain. A total of 12 cutaneous wounds, three on each shoulder and each metatarsus, were created in a standing surgical procedure. Wounds were biopsied on days 2, 4, 7, 14, 21, and 28 after surgery. Clinical parameters (rectal temperature, heart rate, respiratory frequency) and blood levels of white blood cell, serum amyloid A, fibrinogen, and iron were monitored to evaluate the systemic inflammatory response. Local signs of inflammation (swelling, heat, pain) were subjectively assessed, the limb circumference recorded, and temperature of the wound measured by thermometry. Pain was evaluated by a composite measure pain scale (CMPS). The results demonstrated that the wounding procedure elicits an inflammatory response. Day 1 after surgery, two horses scored 2 and 7 units (of 27 units), respectively, on the CMPS, and day 8 after surgery, one horse scored 3 units. The biopsy procedure did not elicit local or systemic signs of inflammation. Based on these findings, it appears that the equine experimental wound model causes mild discomfort and pain manifestations. This information is important for researchers, who consider using the model. To justify the use of an animal model, it should be demonstrated that the expected benefits of the research outweigh the discomfort imposed to the animal.

Osteoblast differentiation of equine induced pluripotent stem cells

Bone fractures occur in horses following traumatic and non-traumatic (bone overloading) events. They can be difficult to treat due to the need for the horse to bear weight on all legs during the healing period. Regenerative medicine to improve fracture union and recovery could significantly improve horse welfare. Equine induced pluripotent stem cells (iPSCs) have previously been derived. Here we show that equine iPSCs cultured for 21 days in osteogenic induction media on an OsteoAssay surface upregulate the expression of osteoblast associated genes and proteins, including COL1A1, SPARC, SPP1, IBSP, RUNX2 and BGALP. We also demonstrate that iPSC-osteoblasts are able to produce a mineralised matrix with both calcium and hydroxyapatite deposition. Alkaline phosphatase activity is also significantly increased during osteoblast differentiation. Although the genetic background of the iPSC donor animal affects the level of differentiation observed after 21 days of differentiation, less variation between lines of iPSCs derived from the same horse was observed. The successful, direct, differentiation of equine iPSCs into osteoblasts may provide a source of cells for future regenerative medicine strategies to improve fracture repair in horses undergoing surgery. iPSC-derived osteoblasts will also provide a potential tool to study equine bone development and disease.

Summary: Horse iPSCs can be turned directly into bone forming cells but the efficiency is affected by the donor horse. Less variability is observed using different iPSC lines derived from the same horse.

Osteopontin -- a promising biomarker for cancer therapy

Osteopontin (OPN), a multifunctional protein, has emerged as a potentially valuable biomarker for diagnosing and treating cancers. Recent research focuses on its involvement in tumor biology including the cell proliferation, survival, angiogenesis, invasion, and metastasis. Understanding the molecular mechanisms and pharmacological effects of OPN in cancer development could lead to new targets for improving cancer diagnosis and treatment. This review explains how the structurally conserved domains of OPN are associated with OPN signaling mediators and CD44, and how the conserved OPN domains determine biological functions. The authors have reviewed representative works of OPN expression in breast cancer and colorectal cancer to elucidate the relationship between OPN and cancer/tumor biology. It has also been shown that the prognostic sensitivity in non-small cell lung cancer, hepatocellular carcinoma, gastric cancer, and ovarian cancer improved compared to the individual marker when OPN was analyzed in conjunction with other markers. The therapeutic approaches based on OPN inhibitors are discussed to illustrate recent research progress. Previous clinical data has indicated that OPN has played a unique role in cancer development, but further investigation is required to understand the underlying mechanism. More clinical trials are also required to examine the applicability and efficacy of OPN inhibitors in cancer therapy.

Osteopontin improves adhesion and migration of human primary renal cortical epithelial cells during wound healing

The aim of the present study was to investigate the effect of osteopontin (OPN) on adhesion and migration in human primary renal cortical epithelial cells during wound healing and Transwell assays. MTT assay was used to examine the cell viability and western blot analysis was used to examine the expression of cytoskeletal proteins and cell adhesion molecules. The results showed that overexpression of OPN had positive effects on the viability, proliferation, adhesion and migration of the human primary renal cortical epithelial cells. In addition, the integrity of the cell membrane and cytoskeleton of the epithelial cells was negatively affected by knockdown of OPN expression. The Transwell migration and a wound healing assays performed using OPN-knockdown cells suggested that OPN had a significant impact on cell migration (P=0.0421) and wound healing (P=0.0333). Therefore, OPN may be a potential target for the therapeutic modulation of skin repair to improve the healing rate and quality of wound healing.

A cross-sectional survey on wounds in horses in New Zealand

AIM

To determine the frequency and type of skin wounds encountered by New Zealand veterinarians in their equine patients, the duration and estimated costs of treatment as well as the expected outcomes for these wounds.

METHODS

An online survey was sent to all veterinarians registered with the New Zealand Equine Veterinary Association. The survey comprised questions on the location and experience of respondents, the number of wound-related cases in relation to the total equine caseload, the type and anatomical location of wounds treated, the frequency, duration and costs of treatments, the outcome of wound treatment and an estimate of the most common causes of death or euthanasia in their equine patients.

RESULTS

The survey response rate was 110/262 (41.9%). The median number of equine cases seen by respondents was 20 (interquartile range (IQR) 6-60) per month; of these, five (IQR 2-10) were wound related. Wounds ranked third after lameness and respiratory disease for the relative frequency with which respondents encountered them. Of 102 respondents 59 (58%) reported that their clients frequently treated wounds incurred by their horse without consulting a veterinarian. Wounds on the distal limb, whether involving only the skin or also deeper structures, were reported by 86/101 (85%) respondents as the most frequently encountered. Wounds in this location also incurred the longest treatment period and were the most prone to develop complications. Finally, wounds ranked second, after colic, as the most common cause of death/euthanasia in the veterinary respondents' equine patients.

CONCLUSIONS

The data obtained via the survey indicate that skin wounds, particularly on the distal limb, are a common occurrence in horses in New Zealand and, when they involve structures underlying the skin, are costly and time-consuming to manage and may lead to decreased performance, retirement or euthanasia. Consequently, we recommend that more effort be devoted to the education of equine veterinarians and owners, and that appropriate research funds be allocated to help improve patient outcomes.