Local Production Of Growth Factors Research Articles

Functional role of glial-derived neurotrophic factor in a mixed allergen murine model of asthma.

Our previous study showed that glial-derived neurotrophic factor (GDNF) expression is upregulated in asthmatic human lungs, and GDNF regulates calcium responses through its receptor GDNF family receptor α1 (GFRα1) and RET receptor in human airway smooth muscle (ASM) cells. In this study, we tested the hypothesis that airway GDNF contributes to airway hyperreactivity (AHR) and remodeling using a mixed allergen mouse model. Adult C57BL/6J mice were intranasally exposed to mixed allergens (ovalbumin, Aspergillus, Alternaria, house dust mite) over 4 wk with concurrent exposure to recombinant GDNF, or extracellular GDNF chelator GFRα1-Fc. Airway resistance and compliance to methacholine were assessed using FlexiVent. Lung expression of GDNF, GFRα1, RET, collagen, and fibronectin was examined by RT-PCR and histology staining. Allergen exposure increased GDNF expression in bronchial airways including ASM and epithelium. Laser capture microdissection of the ASM layer showed increased mRNA for GDNF, GFRα1, and RET in allergen-treated mice. Allergen exposure increased protein expression of GDNF and RET, but not GFRα1, in ASM. Intranasal administration of GDNF enhanced baseline responses to methacholine but did not consistently potentiate allergen effects. GDNF also induced airway thickening, and collagen deposition in bronchial airways. Chelation of GDNF by GFRα1-Fc attenuated allergen-induced AHR and particularly remodeling. These data suggest that locally produced GDNF, potentially derived from epithelium and/or ASM, contributes to AHR and remodeling relevant to asthma.NEW & NOTEWORTHY Local production of growth factors within the airway with autocrine/paracrine effects can promote features of asthma. Here, we show that glial-derived neurotrophic factor (GDNF) is a procontractile and proremodeling factor that contributes to allergen-induced airway hyperreactivity and tissue remodeling in a mouse model of asthma. Blocking GDNF signaling attenuates allergen-induced airway hyperreactivity and remodeling, suggesting a novel approach to alleviating structural and functional changes in the asthmatic airway.

Proprotein convertase furin inhibits matrix metalloproteinase 13 in a TGF\u03b2-dependent manner and limits osteoarthritis in mice

Cartilage loss in osteoarthritis (OA) results from altered local production of growth factors and metalloproteases (MMPs). Furin, an enzyme involved in the protein maturation of MMPs, might regulate chondrocyte function. Here, we tested the effect of furin on chondrocyte catabolism and the development of OA. In primary chondrocytes, furin reduced the expression of MMP-13, which was reversed by treatment with the furin inhibitor α1-PDX. Furin also promoted the activation of Smad3 signaling, whereas activin receptor-like kinase 5 (ALK5) knockdown mitigated the effects of furin on MMP-13 expression. Mice underwent destabilization of the medial meniscus (DMM) to induce OA, then received furin (1 U/mice), α1-PDX (14 µg/mice) or vehicle. In mice with DMM, the OA score was lower with furin than vehicle treatment (6.42 ± 0.75 vs 9.16 ± 0.6, p < 0.01), and the number of MMP-13(+) chondrocytes was lower (4.96 ± 0.60% vs 20.96 ± 8.49%, p < 0.05). Moreover, furin prevented the increase in ALK1/ALK5 ratio in cartilage induced by OA. Conversely, α1-PDX had no effect on OA cartilage structure. These results support a protective role for furin in OA by maintaining ALK5 receptor levels and reducing MMP-13 expression. Therefore, furin might be a potential target mediating the development of OA.

Parathyroid hormone gene-activated matrix with DFDBA/collagen composite matrix enhances bone regeneration in rat calvarial bone defects

BackgroundGene-activated matrix (GAM) induces sustained local production of growth factors to promote tissue regeneration. GAM contains a plasmid DNA (pDNA) encoding target proteins that is physically entrapped within a biodegradable matrix carrier. GAM with a pDNA encoding the first 34 amino acids of parathyroid hormone (PTH 1–34) and a collagen matrix enhances bone regeneration in long bone defects. Demineralized freeze-dried bone allograft (DFDBA) is a widely used osteoinductive bone graft. The present study determined the osteogenic effects of PTH-GAM with a collagen or DFDBA/collagen composite (D/C) matrix for treating craniofacial bone defects. MethodsWe constructed a pDNA encoding human PTH 1–34 and performed cyclic AMP ELISA to verify the bioactivity of PTH 1–34. Next, we generated a D/C matrix and PTH-GAMs containing a collagen matrix (PTH-C-GAM) or D/C matrix (PTH-D/C-GAM). Rats with critical-sized calvarial bone defects were divided into four groups, namely, untreated rats (sham group) and rats grafted with D/C matrix, PTH-C-GAM, or PTH-D/C-GAM (D/C, PTH-C-GAM, or PTH-D/C-GAM groups, respectively). PTH expression was determined by performing immunohistochemical staining after 4 and 8 weeks. New bone formation was evaluated by performing radiography, dual-energy X-ray absorptiometry, microcomputed tomography, and histological examination. ResultsPTH pDNA-transfected cells secreted bioactive PTH 1–34. Moreover, PTH was expressed at 4 and 8 weeks after the surgery in rats in the PTH-C-GAM group but not in rats in the D/C group. New bone formation in the calvarial bone defects, from more to less, was in the order of PTH-D/C-GAM, PTH-C-GAM, D/C, and sham groups. ConclusionOur results indicate that PTH-GAM with a collagen matrix promotes local PTH production for at least 8 weeks and bone regeneration in craniofacial bone defect. Moreover, our results indicate that replacement of the collagen matrix with the D/C matrix improves the osteogenic effects of PTH-GAM.

Effect of sustained PDGF nonviral gene delivery on repair of tooth-supporting bone defects

Recombinant human platelet-derived growth factor-BB (rhPDGF-BB) promotes soft tissue and bone healing, and is FDA-approved for treatment of diabetic ulcers and periodontal defects. The short half-life of topical rhPDGF-BB protein application necessitates bolus, high-dose delivery. Gene therapy enables sustained local growth factor production. A novel gene activated matrix delivering polyplexes of polyethylenimine (PEI)-plasmid DNA (pDNA) encoding PDGF was evaluated for promotion of periodontal wound repair in vivo. PEI-pPDGF-B polyplexes were tested in human periodontal ligament fibroblasts (hPLFs) and gingival fibroblasts (hGFs) for cell viability and transfection efficiency. Collagen scaffolds containing PEI-pPDGF-B polyplexes at two doses, rhPDGF-BB, PEI-vector, or collagen-alone were randomly delivered to experimentally-induced tooth-supporting periodontal defects in a rodent model. Mandibulae were harvested at 21-days for histologic observation and histomorphometry. PEI-pPDGF-B polyplexes were biocompatible to cells tested and ELISA confirmed the functionality of transfection. Significantly greater osteogenesis was observed for collagen-alone and rhPDGF-BB versus the PEI-containing groups. Defects treated with sustained PDGF gene delivery demonstrated delayed healing coupled with sustained inflammatory cell infiltrates lateral to the osseous defects. Continuous PDGF-BB production by non-viral gene therapy could have delayed bone healing. This non-viral gene delivery system in this model appeared to prolong inflammatory response, slowing alveolar bone regeneration in vivo.

Peran Terapi Akupunktur pada Nyeri Tulang Metastasis

ABSTRACTBone pain caused by cancer is a common complication in bone metastasis. Bone pain has the characteristic triad of pain including continuous pain, spontaneous pain and incident pain. Various mechanisms that allow bone metastasis can cause pain have been reported. These mechanisms include the possibility of local production of growth factors and cytokines. The management of the pain bone metastasis include aspects of pharmacological and non-pharmacological therapies. Acupuncture can play a role in the treatment of bone metastasis pain through modulation of various neurotransmitters and increase the production of endogenous opioids that can cause analgesika effect. This paper describes a male patient aged 62 years old with painful bone metastasis who experience an improvement after acupuncture therapy, with the goal of providing information on the possible use of acupuncture for painful bone metastasis. ABSTRAKNyeri tulang yang disebabkan oleh kanker merupakan suatu komplikasi yang sering terjadi pada metastasis tulang. Nyeri tulang ini memiliki karakteristik trias nyeri, yaitu nyeri terus-menerus, nyeri spontan, dan nyeri insiden. Berbagai mekanisme yang memungkinkan metastasis tulang dapat menyebabkan rasa nyeri telah dilaporkan. Mekanisme ini termasuk kemungkinan adanya produksi lokal faktor pertumbuhan dan sitokin. Tata laksana pada nyeri tulang metastasis meliputi aspek terapi farmakologis dan nonfarmakologis. Akupunktur dapat berperan dalam terapi nyeri tulang metastasis melalui modulasi berbagai neurotransmitter dan meningkatkan pengeluaran endogen opioid sehingga menimbulkan efek analgesik. Makalah ini memaparkan pasien laki-laki berusia 62 tahun dengan nyeri tulang metastasis yang mengalami perbaikan setelah terapi akupunktur, dengan tujuan memberikan informasi kemungkinan penggunaan akupunktur pada nyeri metastasis tulang.

Molecular Identity of Human Outer Radial Glia during Cortical Development

Radial glia, the neural stem cells of the neocortex, are located in two niches: the ventricular zone and outer subventricular zone. Although outer subventricular zone radial glia may generate the majority of human cortical neurons, their molecular features remain elusive. By analyzing gene expression across single cells, we find that outer radial glia preferentially express genes related to extracellular matrix formation, migration, and stemness, including TNC, PTPRZ1, FAM107A, HOPX, and LIFR. Using dynamic imaging, immunostaining, and clonal analysis, we relate these molecular features to distinctive behaviors of outer radial glia, demonstrate the necessity of STAT3 signaling for their cell cycle progression, and establish their extensive proliferative potential. These results suggest that outer radial glia directly support the subventricular niche through local production of growth factors, potentiation of growth factor signals by extracellular matrix proteins, and activation of self-renewal pathways, thereby enabling the developmental and evolutionary expansion of the human neocortex.

Growth factors for the treatment of ischemic brain injury (growth factor treatment).

In recent years, growth factor therapy has emerged as a potential treatment for ischemic brain injury. The efficacy of therapies that either directly introduce or stimulate local production of growth factors and their receptors in damaged brain tissue has been tested in a multitude of models for different Central Nervous System (CNS) diseases. These growth factors include erythropoietin (EPO), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor (IGF-1), among others. Despite the promise shown in animal models, the particular growth factors that should be used to maximize both brain protection and repair, and the therapeutic critical period, are not well defined. We will review current pre-clinical and clinical evidence for growth factor therapies in treating different causes of brain injury, as well as issues to be addressed prior to application in humans.

Radial glia require PDGFD-PDGFRβ signalling in human but not mouse neocortex.

Evolutionary expansion of the human neocortex underlies many of our unique mental abilities. This expansion has been attributed to the increased proliferative potential1, 2 of radial glia (RG; i.e. neural stem cells) and their subventricular dispersion from the periventricular niche3, 4, 5 during neocortical development. Such adaptations may have evolved through gene expression changes in RG. However, whether or how RG gene expression varies between humans and other species is unknown. Here we show that the transcriptional profiles of human and mouse neocortical RG are broadly conserved during neurogenesis, yet diverge for specific signaling pathways. By analyzing differential gene coexpression relationships between the species, we demonstrate that the growth factor PDGFD is specifically expressed by RG in human, but not mouse, corticogenesis. We further show that the expression domain of PDGFRß, the cognate receptor6, 7 for PDGFD, is evolutionarily divergent, with high expression in the germinal region of dorsal human neocortex but not in the mouse. Pharmacological inhibition of PDGFD/PDGFRß signaling in slice culture prevents normal cell cycle progression of neocortical RG in human, but not mouse. Conversely, injection of recombinant-PDGFD or ectopic expression of constitutively active PDGFRß in developing mouse neocortex increases the proportion of RG and their subventricular dispersion. These findings highlight the requirement of PDGFD/PDGFRß signaling for human neocortical development and suggest that local production of growth factors by RG supports the expanded germinal region and progenitor heterogeneity of species with large brains.

Study of capillary network directionality and irrigation of hypoxic tissue in an angiogenesis lattice model

To shed light on the understanding of the angiogenesis process, we study a simplified lattice model for the capillary network formation between an existing blood vessel and an initially hypoxic tissue. We consider that the cells of the tissue surface can release growth factors that will diffuse, leading to the formation of new capillaries that ultimately arrive at the tissue. Additionally, we consider the local production of growth factors by the growing capillary network. We also propose the existence of an inhibition mechanism at the hypoxic surface, i.e., a fixed number of neighboring sites of an already irrigated site of the hypoxic tissue stop releasing growth factors due to the arrival of nutrients. Particularly, the goal of this work is to study the effect of the release of local growth factors and the inhibition mechanism on properties such as the directionality of the growing network and the irrigation of the hypoxic tissue. Therefore we propose the quantification of these two relevant features for angiogenesis modeling. We establish a relationship between the model behavior without the release of local growth factors in the presence of the inhibition mechanism and a normal angiogenesis process. In this situation, the model gives a directional capillary network and a good irrigation of the hypoxic tissue. On the other hand, for a large number of released local growth factors in the absence of the inhibition mechanism, the model could be appropriate for the description of tumor angiogenesis. In this case, the model provides a rather small directionality for the growing structure, with a worse degree of irrigation of the hypoxic tissue, as well as a more tortuous capillary network with many closed branches and loops.

Correlation between benign prostatic hyperplasia and inflammation

This review aims to evaluate the available evidence on the role of prostatic inflammation in the pathogenesis and progression of benign prostatic hyperplasia (BPH). Although there is still no evidence of a causal relation, accumulating evidence suggests that inflammation may contribute to the development of BPH and lower urinary tract symptoms (LUTS). Inflammatory infiltrates are frequently observed in prostate tissue specimens from men with BPH and the presence or degree of inflammation has been found to be correlated with prostate volume and weight. The inflammatory injury may contribute to cytokine production by inflammatory cells driving local growth factor production and angiogenesis in the prostatic tissue. This proinflammatory microenvironment is closely related to BPH stromal hyperproliferation and tissue remodeling with a local hypoxia induced by increased oxygen demands by proliferating cells which supports chronic inflammation as a source of oxidative stress leading to tissue injury in infiltrating area. Although the pathogenesis of BPH is not yet fully understood and several mechanisms seem to be involved in the development and progression, recent studies strongly suggest that BPH is an immune inflammatory disease. The T-cell activity and associated autoimmune reaction seem to induce epithelial and stromal cell proliferation. Further understanding of the role of inflammation in BPH and clinical detection of this inflammation will expand the understanding of BPH pathogenesis and its histologic and clinical progression, allow risk stratification for patients presenting with BPH-related LUTS, and suggest novel treatment strategies.

Gene Therapy in Cardiovascular Research

In less than 40 years of the first human gene being isolated, which involves putting isolated and manipulated DNA (genes) back into individuals for treatments of genetic diseases. Gene therapy is now more widely accepted to encompass all forms of therapeutic intervention in which DNA is used to alter the overall pattern of gene expression within an organ. Potential applications of gene therapy are widespread and implications for the management of various human diseases are becoming available. Approaches are being developed to overcome difficulties and identify a number of potential applications (1). The management of cardiovascular diseases includes the treatment of genetic diseases related to disorders of lipid metabolism and of acquired disease focusing on atherosclerosis and restenosis following angioplasty, thus, the introduction of DNA into the arterial wall. It is now relatively well accepted that much of human disease can and should be treated at the level of underlying genetic manipulation. Much of the theoretical basis of gene therapy are going to be worked out step by step (2). What we face now is the difficult task of developing the technology required to put these ideas into an actual clinical situation. Although it is relatively easy to get DNA into cells under experimental conditions, it remains much more difficult to do so with the efficiency required for therapy in clinics. What then are the implications for cardiovascular disease? Several approaches have also been made to modify cell phenotype including inhibition of gene function associated with cell proliferation and to arrest the progress of atherosclerosis and restenosis, and the local production of growth factors to promote angiogenesis (e.g., VEGF. These procedures are of potential use in the treatment of peripheral vascular diseases and myocardial ischemia. Although DNA is taken up by cardiac myocytes relatively efficiently, it is currently difficult to envisage global treatment of different parts of a diseased myocardium. For instance, the direct injection of genes leads to highly localized DNA uptake; adenovirus provides potential for more global DNA transfer but elicits a strong immune response in the body. There is an increasing interest in the molecular regulation of introduced gene(s) to elicit regionally specific effects i.e., directed for to regions of hypoxia or other stress. Approaches most likely to succeed in gene therapy remain a subject for speculation and based on experimental findings. We should also take caution and not only overestimate the importance of gene therapy at this early, but promising stage. These are exciting times but it takes additional and substantial effort before gene therapy makes real impact in humans. What appears certain is that cardiovascular diseases will be a major of therapeutic applications.

Growth factors and myometrium: biological effects in uterine fibroid and possible clinical implications

Growth factors are proteins secreted by a number of cell types that are capable of modulating cellular growth, proliferation and cellular differentiation. It is well accepted that uterine cellular events such as proliferation and differentiation are regulated by sex steroids and their actions in target tissues are mediated by local production of growth factors acting through paracrine and/or autocrine mechanisms. Myometrial mass is ultimately modified in pregnancy as well as in tumour conditions such as leiomyoma and leiomyosarcoma. Leiomyomas, also known as fibroids, are benign tumours of the uterus, considered to be one of the most frequent causes of infertility in reproductive years in women. For this review, we searched the database MEDLINE and Google Scholar for articles with content related to growth factors acting on myometrium; the findings are hereby reviewed and discussed. Different growth factors such as epidermal growth factor (EGF), transforming growth factor-α (TGF-α), heparin-binding EGF (HB-EGF), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), platelet-derived growth factor (PDGF) and TGF-β perform actions in myometrium and in leiomyomas. In addition to these growth factors, activin and myostatin have been recently identified in myometrium and leiomyoma. Growth factors play an important role in the mechanisms involved in myometrial patho-physiology.

Growth factors for periodontal regeneration

Periodontal tissue repair and regeneration are regulated by the local production of growth factors. However, naturally produced growth factors may not be sufficient to optimally stimulate periodontal regeneration. Exogenous growth factors can be used to supplement natural growth factors in wound healing. The authors focus on describing the mechanisms of five growth factors in periodontal regeneration: platelet-derived growth factor; fibroblast growth factor; transforming growth factor-beta; insulinlike growth factor; and bone morphogenetic protein. The objective is to encourage strategies to exploit growth factors in the stimulation of cells in periodontal regeneration, which should result from continued in vivo animal studies.

Signals mediating skeletal muscle remodeling by resistance exercise: PI3-kinase independent activation of mTORC1

For over 10 years, we have known that the activation of the mammalian target of rapamycin complex 1 (mTORC1) has correlated with the increase in skeletal muscle size and strength that occurs following resistance exercise. Initial cell culture and rodent models of muscle growth demonstrated that the activation of mTORC1 is common to hypertrophy induced by growth factors and increased loading. The further observation that high loads increased the local production of growth factors led to the paradigm that resistance exercise stimulates the autocrine production of factors that act on membrane receptors to activate mTORC1, and this results in skeletal muscle hypertrophy. Over the last few years, there has been a paradigm shift. From both human and rodent studies, it has become clear that the phenotypic and molecular responses to resistance exercise occur in a growth factor-independent manner. Although the mechanism of load-induced mTORC1 activation remains to be determined, it is clear that it does not require classical growth factor signaling.

The dependence of MG63 osteoblast responses to (meth)acrylate-based networks on chemical structure and stiffness

The cell response to an implant is regulated by the implant’s surface properties including topography and chemistry, but less is known about how the mechanical properties affect cell behavior. The objective of this study was to evaluate how the surface stiffness and chemistry of acrylate-based copolymer networks affect the in vitro response of human MG63 pre-osteoblast cells. Networks comprised of poly(ethylene glycol) dimethacrylate (PEGDMA; Mn ∼750) and diethylene glycol dimethacrylate (DEGDMA) were photopolymerized at different concentrations to produce three compositions with moduli ranging from 850 to 60 MPa. To further decouple chemistry and stiffness, three networks comprised of 2-hydroxyethyl methacrylate (2HEMA) and PEGDMA or DEGDMA were also designed that exhibited a range of moduli similar to the PEGDMA–DEGDMA networks. MG63 cells were cultured on each surface and tissue culture polystyrene (TCPS), and the effect of copolymer composition on cell number, osteogenic markers (alkaline phosphatase specific activity and osteocalcin), and local growth factor production (OPG, TGF-β1, and VEGF-A) were assessed. Cells exhibited a more differentiated phenotype on the PEGDMA–DEGDMA copolymers compared to the 2HEMA–PEGDMA copolymers. On the PEGDMA–DEGDMA system, cells exhibited a more differentiated phenotype on the stiffest surface indicated by elevated osteocalcin compared with TCPS. Conversely, cells on 2HEMA–PEGDMA copolymers became more differentiated on the less stiff 2HEMA surface. Growth factors were regulated in a differential manner. These results indicate that copolymer chemistry is the primary regulator of osteoblast differentiation, and the effect of stiffness is secondary to the surface chemistry.

Growth factors in benign prostatic hyperplasia: Basic science implications

Benign prostatic hyperplasia (BPH) is the most common proliferative disease of the prostate of men in the United States. The histopathology of BPH strongly implicates local paracrine and autocrine growth factors and inflammatory cytokines in its pathogenesis. A complex milieu of growth-regulatory proteins includes members of the fibroblast, insulin-like, and transforming growth factor families. It appears that these proteins and downstream effector molecules, in addition to a variety of interleukins, are overexpressed in BPH and, working together, create a landscape of increased stromal and epithelial growth and mesenchymal transdifferentiation that leads to disease progression. Inflammation, commonly present in BPH, may contribute to tissue injury, and cytokines produced by inflammatory cells may serve to drive local growth factor production and angiogenesis in the tissues as a "wound healing" response. As we begin to unravel the precise mechanisms involved, new treatments for BPH aimed at these interacting pathways may emerge.

Dendritic Epidermal T Cells Promote Wound Healing by Production of Vascular Endothelial Growth Factor Mediated by HIF‐1α Signaling

Local hypoxia is general consequence of an acute skin wound due to vascular disruption and high oxygen consumption by cells at the edge of the wound. The resident γδ T cells in the skin, Dendritic Epidermal T Cells (DETC), are known to support local tissue homeostasis and wound repair by local production of growth factors, such as keratinocyte growth factors (KGFs) and insulin‐like growth factor (IGF)‐1. We have analyzed the functional role of DETC in response to local tissue hypoxia generated by an acute skin wound. The hypoxic status of the skin wound induced HIF‐1α expression in DETC. HIF‐1α signalling during hypoxia induced expression of vascular endothelial growth factor (VEGF) by DETC. Wound healing was impaired after HIF‐1α gene‐silencing in DETC and this impairment was rescued by VEGF administration. Together this data demonstrates that acute skin wound induces HIF‐1α signaling in DETC, which promote VEGF production with the result of enhancing skin wound healing.Grant: NIH‐AI‐36964

Treatment of diabetic wounds with fetal murine mesenchymal stromal cells enhances wound closure

Diabetes impairs multiple aspects of the wound-healing response. Delayed wound healing continues to be a significant healthcare problem for which effective therapies are lacking. We have hypothesized that local delivery of mesenchymal stromal cells (MSC) at a wound might correct many of the wound-healing impairments seen in diabetic lesions. We treated excisional wounds of genetically diabetic (Db-/Db-) mice and heterozygous controls with either MSC, CD45(+) cells, or vehicle. At 7 days, treatment with MSC resulted in a decrease in the epithelial gap from 3.2 +/- 0.5 mm in vehicle-treated wounds to 1.3 +/- 0.4 mm in MSC-treated wounds and an increase in granulation tissue from 0.8 +/- 0.3 mm(2) to 2.4 +/- 0.6 mm(2), respectively (mean +/- SD, P < 0.04). MSC-treated wounds also displayed a higher density of CD31(+) vessels and exhibited increases in the production of mRNA for epidermal growth factor, transforming growth factor beta 1, vascular endothelial growth factor, and stromal-derived growth factor 1-alpha. MSC also demonstrated greater contractile ability than fibroblast controls in a collagen gel contraction assay. The effects of locally applied MSC are thus sufficient to improve healing in diabetic mice. Possible mechanisms of this effect include augmented local growth-factor production, improved neovascularization, enhanced cellular recruitment to wounds, and improved wound contraction.

Multipotent mesenchymal stem cells reduce interstitial fibrosis but do not delay progression of chronic kidney disease in collagen4A3-deficient mice

Multipotent mesenchymal stem or stromal cells (MSC) have shown to improve outcome of acute renal injury models, but whether MSC can delay renal failure in chronic kidney disease is not known. We injected primary MSC or saline into mice that lack the alpha3-chain of type IV collagen (COL4A3), a model of chronic kidney disease with close similarities to human Alport disease. Weekly injections of MSC from week 6 to 10 of life prevented the loss of peritubular capillaries and reduced markers of renal fibrosis, that is, interstitial volume, numbers of smooth muscle actin-positive interstitial cells, and interstitial collagen deposits as compared to saline-injected COL4A3-deficient mice. However, renal function, that is, blood urea nitrogen, creatinine levels, proteinuria as well as survival of COL4A3-deficient mice were not affected by MSC injections. Although MSC were found to localize to kidneys of COL4A3-deficient mice after injection, differentiation into renal cells was not detected. However, MSC expressed growth factors, that is, vascular endothelial growth factor (VEGF) and bone morphogenetic protein-7 under basal culture conditions. In fact, VEGF mRNA levels were increased in kidneys of MSC-injected COL4A3-deficient mice and MSC supernatants enhance endothelial cell proliferation in vitro. Thus, weekly injections with MSC prevent loss of peritubular capillaries possibly owing to local production of growth factors rather than by differentiation into renal cells. The maintenance of interstitial vasculature is associated with less interstitial fibrosis but, is insufficient to delay renal failure and survival of COL4A3-deficient mice.

The use of heparan sulfate to augment fracture repair in a rat fracture model

Fracture healing is a complex process regulated by numerous growth and adhesive factors expressed at specific stages during healing. The naturally occurring, cell surface-expressed sugar, heparan sulfate (HS), is known to bind to and potentiate the effects of many classes of growth factors, and as such, may be a potential candidate therapy for enhancing bone repair. This study investigated the local application of bone-derived HS in the repair of rat femoral fractures. After 2 weeks, there was a significant increase in the callus size of rats administered with 5 microg HS compared to the control and 50 microg HS groups, presumably due to increased trabecular bone volume rather than increased cartilage production. In addition, 5 microg HS increased the expression of ALP, Runx2, FGF-1, IGF-II, TGF-beta1, and VEGF. It is hypothesized that these increases resulted from changes in HS-mediated receptor/ligand interactions that increase local growth factor production to augment bone formation. The findings of this study demonstrate the anabolic potential of HS in bone repair by recruiting and enhancing the production of endogenous growth factors at the site of injury.