Effects of VEGF and MSCs on vascular regeneration in a trauma model in rats

Assessment of therapeutic efficacy of adipose tissue-derived mesenchymal stem cells administration in hyperlipidemia-induced aortic atherosclerosis in adult male albino rats

Atherosclerosis (AS) is a common disease seriously detrimental to human health. AS is a chronic progressive disease related to inflammatory reactions. The present study aimed to characterize and evaluate the effects of adipose tissue stem cells (ADSCs) in high-fat diet-induced atherosclerosis in a rat model. The present study comprises thirty-six rats and they were divided into three groups: the control group, the high-fat diet (HFD) group; which received a high-fat diet, and the high-fat diet + stem cells (HFD+SC) group; which was fed with a high-fat diet along with the administration of intravenous ADSCs. Food was given to the animals for 20 weeks to establish dyslipidemia models. After 20 weeks, animals were sacrificed by cervical dislocation; blood was collected to measure total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL); aortae were collected to detect morphologic changes. Rats of the HFD group showed a significant increase in body weight (B.Wt), altered lipid profile increased expression of inducible nitric oxide synthase (iNOS), and decreased expression of endothelial nitric oxide synthase (eNOS). However, in HFD+SC there was a significant decrease in body weight gain and an improvement in lipid profile. Histopathological and ultrastructural variations observed in the aorta of the HFD group when treated with ADSCs showed preserved normal histological architecture and reduced atherosclerosis compared with the HFD group. This was evidenced by laboratory, histological, immunohistochemical, and morphometric studies. Thus, ADSCs reduced TC, TG, and LDL, reduced the expression of iNOS, and increased the expression of eNOS. The high-fat diet was likely to cause damage to the wall of blood vessels. Systemically transplanted ADSCs could home to the aorta, and further protect the aorta from HFD-induced damage.

Perfusion in vivo bioreactor promotes regeneration of vascularized tissue-engineered bone

Aim: This study improved the in vivo bioreactor (IVB) for bone regeneration by enhancing stem cell survival and promoting vascularized tissue-engineered bone. Methods: 12 New Zealand rabbits received β-TCP scaffolds with rabbit bone mesenchymal stem cells (BMSCs) implanted. Perfusion IVB with a perfusion electronic pump was compared with the control group using micro-CT, Microfil perfusion, histological staining and RT-PCR for gene expression. Results: Perfusion IVB demonstrated good biocompatibility, increased neoplastic bone tissue, neovascularization and upregulated osteogenic and angiogenesis-related genes in rabbits (p < 0.05). Conclusion: Perfusion IVB holds promise for bone regeneration and tissue engineering in orthopedics and maxillofacial surgery.

Angiogenesis: A Cellular Response to Traumatic Injury

ABSTRACT

The development of new vasculature plays a significant role in a number of chronic disease states, including neoplasm growth, peripheral arterial disease, and coronary artery disease, among many others. Traumatic injury and hemorrhage, however, is an immediate, often dramatic pathophysiologic insult that can also necessitate neovascularization to promote healing. Traditional understanding of angiogenesis involved resident endothelial cells branching outward from localized niches in the periphery. Additionally, there are a small number of circulating endothelial progenitor cells that participate directly in the process of neovessel formation. The bone marrow stores a relatively small number of so-called pro-angiogenic hematopoietic progenitor cells-that is, progenitor cells of a hematopoietic potential that differentiate into key structural cells and stimulate or otherwise support local cell growth/differentiation at the site of angiogenesis. Following injury, a number of cytokines and intercellular processes are activated or modulated to promote development of new vasculature. These processes initiate and maintain a robust response to vascular insult, allowing new vessels to canalize and anastomose and provide timely oxygen delivering to healing tissue. Ultimately as we better understand the key players in the process of angiogenesis we can look to develop novel techniques to promote healing following injury.

Roles of oxygen level and hypoxia-inducible factor signaling pathway in cartilage, bone and osteochondral tissue engineering

The repair and treatment of articular cartilage injury is a huge challenge of orthopedics. Currently, most of the clinical methods applied in treating cartilage injuries are mainly to relieve pains rather than to cure them, while the strategy of tissue engineering is highly expected to achieve the successful repair of osteochondral defects. Clear understandings of the physiological structures and mechanical properties of cartilage, bone and osteochondral tissues have been established, but the understanding of their physiological heterogeneity still needs further investigation. Apart from the gradients in the micromorphology and composition of cartilage-to-bone extracellular matrixes, an oxygen gradient also exists in natural osteochondral tissue. The response of hypoxia-inducible factor (HIF)-mediated cells to oxygen would affect the differentiation of stem cells and the maturation of osteochondral tissue. This article reviews the roles of oxygen level and HIF signaling pathway in the development of articular cartilage tissue, and their prospective applications in bone and cartilage tissue engineering. The strategies for regulating HIF signaling pathway and how these strategies finding their potential applications in the regeneration of integrated osteochondral tissue are also discussed.

In situ activated mesenchymal stem cells (MSCs) by bioactive hydrogels for myocardial infarction treatment

Stem-cell therapy has been proved as a promising strategy for myocardial infarction (MI) treatment. However, the therapeutic efficacy is mainly limited by the cellular activity of transplanted mesenchymal stem cells (MSCs). In this study, a novel bioglass (BG)/γ-polyglutamic acid (γ-PGA)/chitosan (CS) hydrogel was obtained by in situ adding BG to stimulate the imine bond formation. And the effect of the composite hydrogel on MI therapeutic efficacy was evaluated in a rat acute myocardial infarction (AMI) model in vivo and the possible mechanism of the BG/γ-PGA/CS hydrogel for the stimulation of the intercellular interaction between MSCs and cardiomyocytes (CMs) was explored by a MSC and CM co-culture experiment in vitro. The implantation of the MSC loaded BG/γ-PGA/CS composite hydrogel in the mice AMI model showed a significant improvement in the therapeutic efficacy with improved cardiac function, attenuation of heart remodeling, reduced cardiomyocyte apoptosis and accelerated vascularization. The in vitro cell experiments demonstrated that the BG/γ-PGA/CS hydrogel activated the intercellular interaction between MSCs and CMs, which resulted in reduced cell apoptosis and enhanced angiogenesis. Silicate based bioactive hydrogels activated MSCs and cell-cell interactions in cardiac tissue after AMI and significantly enhanced the efficacy, which suggests that this bioactive hydrogel based approach is an effective way to enhance stem-cell therapy.

The effects of mesenchymal stem cells on the structure and contractile force of the carotid artery in a rat aneurysm model

Background/aim: An aneurysm is a pathological enlargement of an artery characterized by the thinning of the elastic fiber layer in the tunica media. Because the aneuritic artery wall is weakened, these vessels can rupture and cause serious bleeding. Surgical methods are often used for the treatment of aneurysms. However, cell-based therapies are less invasive and potentially safer alternatives. In this study, the therapeutic efficacy of rat adipose tissue-derived mesenchymal stem cells (MSCs) was investigated in a new carotid artery aneurysm model.Materials and methods: Arteries were pretreated with elastase to create aneurysms. Gelatin matrices containing MSCs were applied to the outer surface of the elastase-treated carotid artery sections.Results: Healing of the aneuritic arteries for which MSC applications were performed was significantly better than in the aneuritic group. The histological structure of the vessels was largely reconstituted, and the contractile force of the MSC-treated group was similar to the untreated healthy group.Conclusions: Application of MSCs facilitates the healing of aneurysms. Hereby, MSC application could be a promising approach for clinical applications after further validation processes are concluded.

Detrimental effect of Hypoxia-inducible factor-1α-induced autophagy on multiterritory perforator flap survival in rats

Hypoxia-inducible factor-1α (HIF-1α) plays a key role in angiogenesis, improves flap survival, and activates autophagy. The effect of HIF-1α-induced autophagy is still debatable. Thus, we investigated the effect of HIF-1α-induced autophagy on multiterritory perforator flap survival. In this study, 99 male Sprague-Dawley rats received multiterritory perforator flap procedure and were divided into three groups with 33 each. The dimethyloxalylglycine (DMOG) plus 3-methyladenine (3-MA) group received intraperitoneal injection of DMOG (40 mg/kg) and 3-MA (10 mg/kg). The DMOG group and control group received comparative DMOG and saline respectively. On postoperative day (POD) 7, HIF-1α’s activities of flap survival and perfusion improvement were confirmed in DMOG group, however, its positive effects were further enhanced by co-administration of autophagy inhibitor, 3-MA. On POD 1, vascular endothelial growth factor, mean microvascular density and blood perfusion were not affected by HIF-1α up-regulation or autophagy inactivation. However, HIF-1α-induced autophagy augments apoptosis and oxidative stress. The increased level of apoptosis and oxidative stress was reversed by 3-MA and resulted in further flap survival improvement. In conclusion, HIF-1α-induced autophagy has a detrimental effect on multiterritory perforator flap survival and the flap survival was determined by the combined effects of ischemia and reperfusion injury.

Monitoring of vascular endothelial growth factor and its soluble receptor levels in early trauma

BACKGROUND

This clinical observation study aimed to investigate the relationship between the serum levels of vascular endothelial growth factor (VEGF) and its soluble receptors with the severity and the occurrence of late acute respiratory distress syndrome (ARDS) in early trauma.

METHODS

Sixty patients with multiple injuries were divided into three groups according to the Injury Severity Score (ISS) and the serum levels of VEGF, soluble VEGF receptor 1 (sVEGFR1), and sVEGFR2, were measured. Ten healthy people were recruited as controls. The incidence of late ARDS was also monitored, and its relationship to the above measures analyzed.

RESULTS

VEGF was not associated with ISS (p > 0.05); sVEGFR1 was positively associated with ISS (r = 0.459, p < 0.0001); however, sVEGFR2 was negatively associated with ISS (r = 0.510, p < 0.0001). The serum VEGF levels between the ARDS group and the non-ARDS group showed no significant difference (p > 0.05). sVEGFR1 in the ARDS group was significantly higher than that in the non-ARDS group (p < 0.0001), and sVEGFR2 in the ARDS group was significantly lower than that in the non-ARDS group (p < 0.0001).

CONCLUSION

In conclusion, the increasing of sVEGFR1 and the decreasing of sVEGFR2 in early trauma might be closely related to the occurrence of late ARDS.

LEVEL OF EVIDENCE

Prognostic study, level III.

Trauma and Stem Cells: Biology and Potential Therapeutic Implications

Trauma may cause irreversible tissue damage and loss of function despite current best practice. Healing is dependent both on the nature of the injury and the intrinsic biological capacity of those tissues for healing. Preclinical research has highlighted stem cell therapy as a potential avenue for improving outcomes for injuries with poor healing capacity. Additionally, trauma activates the immune system and alters stem cell behaviour. This paper reviews the current literature on stem cells and its relevance to trauma care. Emphasis is placed on understanding how stem cells respond to trauma and pertinent mechanisms that can be utilised to promote tissue healing. Research involving notable difficulties in trauma care such as fracture non-union, cartilage damage and trauma induced inflammation is discussed further.

Umbilical Cord-Derived Mesenchymal Stem Cells Relieve Hindlimb Ischemia through Enhancing Angiogenesis in Tree Shrews

Hindlimb ischemia is still a clinical problem with high morbidity and mortality. Patients suffer from consequent rest pain, ulcers, cool limbs, and even amputation. Angiogenesis is a promising target for the treatment of ischemic limbs, providing extra blood for the ischemic region. In the present study, we investigated the role of umbilical cord-derived mesenchymal stem cells (UC-MSCs) in regulating angiogenesis and relieving hindlimb ischemia. UC-MSCs were isolated from the umbilical cord of tree shrews. Angiography results showed that UC-MSCs injection significantly promoted angiogenesis in tree shrews. Moreover, the ankle brachial index, transcutaneous oxygen pressure, blood perfusion, and capillary/muscle fiber ratio were all markedly increased by the application of UC-MSCs. In addition, the conditioned culture of human umbilical vein endothelial cells using medium collected from UC-MSCs showed higher expression of angiogenic markers and improved migration ability. In short, the isolated UC-MSCs notably contributed to restoring blood supply and alleviating the symptoms of limb ischemia through enhancing angiogenesis.

Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.

LL-37 stimulates the functions of adipose-derived stromal/stem cells via early growth response 1 and the MAPK pathway

Background

LL-37 is a naturally occurring antimicrobial peptide found in the wound bed and assists wound repair. No published study has characterized the role of LL-37 in the function(s) of human mesenchymal stem cells (MSCs). This study investigated the functions of adipose-derived stromal/stem cells (ASCs) activated by LL-37 by performing both in vitro assays with cultured cells and in vivo assays with C57BL/6 mice with hair loss.

Methods

Human ASCs were isolated from healthy donors with written informed consent. To examine the effects of LL-37 on ASC function, cell proliferation and migration were measured by a cell counting kit (CCK-8) and a Transwell migration assay. Early growth response 1 (EGR1) mRNA expression was determined by microarray and real-time PCR analyses. The protein levels of EGR1 and regenerative factors were analyzed by specific enzyme-linked immunosorbent assays and western blotting.

Results

LL-37 treatment enhanced the proliferation and migration of human ASCs expressing formyl peptide receptor like-1. Microarray and real-time PCR data showed that EGR1 expression was rapidly and significantly increased by LL-37 treatment. LL-37 treatment also enhanced the production of EGR1. Moreover, small interfering RNA-mediated knockdown of EGR1 inhibited LL-37-enhanced ASC proliferation and migration. Activation of mitogen-activated protein kinases (MAPKs) was essential not only for LL-37-enhanced ASC proliferation and migration but also EGR1 expression; treatment with a specific inhibitor of extracellular signal-regulated kinase, p38, or c-Jun N-terminal kinase blocked the stimulatory effect of LL-37. EGR1 has a strong paracrine capability and can influence angiogenic factors in ASCs; therefore, we evaluated the secretion levels of vascular endothelial growth factor, thymosin beta-4, monocyte chemoattractant protein-1, and stromal cell-derived factor-1. LL-37 treatment increased the secretion of these regenerative factors. Moreover, treatment with the conditioned medium of ASCs pre-activated with LL-37 strongly promoted hair growth in vivo.

Conclusions

These findings show that LL-37 increases EGR1 expression and MAPK activation, and that preconditioning of ASCs with LL-37 has a strong potential to promote hair growth in vivo. This study correlates LL-37 with MSC functions (specifically those of ASCs), including cell expansion, cell migration, and paracrine actions, which may be useful in terms of implantation for tissue regeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0313-4) contains supplementary material, which is available to authorized users.

Possible Therapeutic Effect of Stem Cell in Atherosclerosis in Albino Rats. A Histological and Immunohistochemical Study

BACKGROUND

Atherosclerosis is the leading cause of death worldwide. there are no effective approaches to regressing atherosclerosis due to not fully understood mechanisms. Recently, stem cell-based therapies have held promises to various diseases, including vascular diseases.

AIM

The present study aimed at investigating the possible effect of cord blood mesenchymal stem cell (MSC) therapy on atherosclerosis.

MATERIAL AND METHODS

Eighty adult male albino rats were divided into control group (I), atherogenic group (II): subjected to high cholesterol fed diet (200~300 mg/kg body weight) for 12 weeks and 1.8 million units of vitamin D / kg of diet for 6 weeks. Stem cell therapy group (III): injected with stem cells in the tail vein following confirmation of atherosclerosis. Histological, Immunohistochemical and morphometric studies were performed were conducted.

RESULTS

Atherogenic group (II) showed increased aortic thickness, intimal proliferation, smooth muscle proliferation and migration. Increased area % of collagen fibers, iNOS and vimentin immunoreactions were recorded and proved morphometrically. All findings regressed on stem cell therapy.

CONCLUSION

A definite therapeutic effect of mesenchymal stem cells was found on atherosclerosis.