Fig 5 - uploaded by May Griffith
Content may be subject to copyright.
Assessment of vasculature in treated hindlimbs. There was a trend for increased arteriole counts with matrix treatments (A) . Larger arterioles were produced in animals receiving collagen or SDF-1 microsphere-matrix (SDF-1) treatments, with the SDF-1 microsphere-matrix treatment leading to the largest arterioles (B) . C , D , E are representative images of arterioles (indicated by SMA + , red), and counter stained with DAPI (blue). Scale bars = 50 μ m. n = 6-8 

Assessment of vasculature in treated hindlimbs. There was a trend for increased arteriole counts with matrix treatments (A) . Larger arterioles were produced in animals receiving collagen or SDF-1 microsphere-matrix (SDF-1) treatments, with the SDF-1 microsphere-matrix treatment leading to the largest arterioles (B) . C , D , E are representative images of arterioles (indicated by SMA + , red), and counter stained with DAPI (blue). Scale bars = 50 μ m. n = 6-8 

Source publication
Article
Full-text available
Although many regenerative cell therapies are being developed to replace or regenerate ischaemic muscle, the lack of vasculature and poor persistence of the therapeutic cells represent major limiting factors to successful tissue restoration. In response to ischaemia, stromal cell-derived factor-1 (SDF-1) is up-regulated by the affected tissue to st...

Similar publications

Article
Full-text available
Protein Z (PZ) is a vitamin K-dependent coagulation factor without catalytic activity. Evidence points towards PZ as an independent risk factor for the occurrence of human peripheral arterial disease. However, the role of PZ in ischemia-driven angiogenesis and vascular healing processes has not been elucidated so far. Angiogenic potency of PZ was a...

Citations

... Further, they were incorporated into an injectable collagen-based matrix for the treatment of ischemic hindlimb muscle. This local delivery increased the migration of progenitor cells, and also improved the recruitment of angiogenic cells (Kuraitis et al. 2011). ...
Chapter
Soft tissues connect, support, or surround other structures and organs of the body, including skeletal muscles, tendon vessels, and nerves supplying these components. Also, organs such as the heart, brain, liver, and kidney are considered as soft tissues. Acute and chronic injury may cause transient or permanent damage to organs and soft tissues. If the damage is severe, the natural physiological repair and restoration mechanisms are not possible. The repair or regeneration using tissue engineered (TE) scaffolds has been considered as a clinical solution. TE approach involves the replacement of damaged parts using grafts made from natural or synthetic or composite polymers. Choosing the polymer with appropriate biological, physicochemical, and mechanical properties is the key to make a successful TE scaffold, and it is still a challenging task. Moreover, the fabrication technique and choice of cells or growth factors for encapsulation to develop the graft also play a crucial role. Therefore, in this chapter, we have highlighted the grafts developed for engineering soft tissues such as blood vessels, skin, cartilage, intervertebral disc, tendon, and skeletal muscle. We have restricted our focus on electrospun scaffolds, and injectable hydrogels prepared using polymers include collagen (Col), chitosan (CS), hyaluronic acid (HA) alginate (Alg), poly(caprolactone) (PCL), poly(lactic acid) (PLA), poly(glycolic-lactic acid) (PLGA), and their composites. This chapter will help the readers to understand the choice of materials and fabrication techniques for developing successful TE scaffolds for soft tissue engineering applications.
... Moreover, SDF-1α is a potent chemokine upregulated during the early stages of wound healing. It is crucial for the homing of endothelial progenitor cells to ischemic sites and promote local angiogenesis [21][22][23][24]. Therefore, in this study, we seek to investigate if the SDF-1α GAS could be used to enhance the provasculogenic maturation of cocultures of endothelial cells and adipose-derived stem/stromal cells (ADSCs). ...
Article
Full-text available
Novel biomaterials can be used to provide a better environment for cross talk between vessel forming endothelial cells and wound healing instructor stem cells for tissue regeneration. This study seeks to investigate if a collagen scaffold containing a proangiogenic gene encoding for the chemokine stromal-derived factor-1 alpha (SDF-1α GAS) could be used to enhance functional responses in a coculture of human umbilical vein endothelial cells (HUVECs) and human adipose-derived stem/stromal cells (ADSCs). Functional responses were determined by (1) monitoring the amount of junctional adhesion molecule VE-cadherin released during 14 days culture, (2) expression of provasculogenic genes on the 14th day, and (3) the bioactivity of secreted factors on neurogenic human Schwann cells. When we compared our SDF-1α GAS with a gene-free scaffold, the results showed positive proangiogenic determination characterized by a transient yet controlled release of the VE-cadherin. On the 14th day, the coculture on the SDF-1α GAS showed enhanced maturation than its gene-free equivalent through the elevation of provasculogenic genes (SDF-1α—7.4-fold, CXCR4—1.5-fold, eNOS—1.5-fold). Furthermore, we also found that the coculture on SDF-1α GAS secretes bioactive factors that significantly (p < 0.01) enhanced human Schwann cells’ clustering to develop toward Bünger band-like structures. Conclusively, this study reports that SDF-1α GAS could be used to produce a bioactive vascularized construct through the enhancement of the cooperative effects between endothelial cells and ADSCs.
... With clinical application as the goal, synthetically-produced recombinant human collagen was used to circumvent immunogenic reactions that can occur with animal-derived collagen in susceptible patients due to their non-human protein composition, 44 and pathogen transmission risks. Furthermore, our collagen-based biomaterials made for the cornea have been modified for use in other systems, [45][46][47] as similar conditions such as skin ulcers in legs of diabetics, are enormous problems in LMICs. 48 While confirmation in a larger number of patients is needed, we nevertheless demonstrate that implantation with cell-free RHCIII-MPC implants is a safe, reliable option for treating patients at high risk of donor allograft rejection; providing pain relief, and regenerating tissue and nerves. ...
... To be used for CLI treatment, a proper biomaterial should provide a proper biomimetic environment for injected/residing cells to improve the blood supply and ultimately the regeneration of the ischemic tissue. It has been stated that the biomaterials that have been used for delivery of growth factor or cells in animal models of PAD and CLI including fibrin (Layman et al., 2011), alginate (Ruvinov, Leor, & Cohen, 2010), and collagen-based matrix (Kuraitis et al., 2011) may not govern the proper biomimetic environment (DeQuach et al., 2012). It has been hypothesized that developing a proper scaffold not only provides a proper biomimetic environment for restoring muscle mass, but also is proangiogenic per se can avoid the need of exogenous growth factors/therapeutic cells and their complications related to these approaches for CLI treatment (DeQuach et al., 2012). ...
Article
Critical limb ischemia (CLI) is the advanced stage of peripheral artery disease spectrum and is defined by limb pain or impending limb loss because of compromised blood flow to the affected extremity. Current conventional therapies for CLI include amputation, bypass surgery, endovascular therapy, and pharmacological approaches. Although these conventional therapeutic strategies still remain as the mainstay of treatments for CLI, novel and promising therapeutic approaches such as proangiogenic gene/protein therapies and stem cell‐based therapies have emerged to overcome, at least partially, the limitations and disadvantages of current conventional therapeutic approaches. Such novel CLI treatment options may become even more effective when other complementary approaches such as utilizing proper bioscaffolds are used to increase the survival and engraftment of delivered genes and stem cells. Therefore, herein, we address the benefits and disadvantages of current therapeutic strategies for CLI treatment and summarize the novel and promising therapeutic approaches for CLI treatment. Our analyses also suggest that these novel CLI therapeutic strategies show considerable advantages to be used when current conventional methods have failed for CLI treatment.
... With clinical application as the goal, synthetically-produced recombinant human collagen was used to circumvent immunogenic reactions that can occur with animal-derived collagen in susceptible patients due to their non-human protein composition, 44 and pathogen transmission risks. Furthermore, our collagen-based biomaterials made for the cornea have been modified for use in other systems, [45][46][47] as similar conditions such as skin ulcers in legs of diabetics, are enormous problems in LMICs. 48 While confirmation in a larger number of patients is needed, we nevertheless demonstrate that implantation with cell-free RHCIII-MPC implants is a safe, reliable option for treating patients at high risk of donor allograft rejection; providing pain relief, and regenerating tissue and nerves. ...
Article
Full-text available
The severe worldwide shortage of donor organs, and severe pathologies placing patients at high risk for rejecting conventional cornea transplantation, have left many corneal blind patients untreated. Following successful pre-clinical evaluation in mini-pigs, we tested a biomaterials-enabled pro-regeneration strategy to restore corneal integrity in an open-label observational study of six patients. Cell-free corneal implants comprising recombinant human collagen and phosphorylcholine were grafted by anterior lamellar keratoplasty into corneas of unilaterally blind patients diagnosed at high-risk for rejecting donor allografts. They were followed-up for a mean of 24 months. Patients with acute disease (ulceration) were relieved of pain and discomfort within 1–2 weeks post-operation. Patients with scarred or ulcerated corneas from severe infection showed better vision improvement, followed by corneas with burns. Corneas with immune or degenerative conditions transplanted for symptom relief only showed no vision improvement overall. However, grafting promoted nerve regeneration as observed by improved touch sensitivity to near normal levels in all patients tested, even for those with little/no sensitivity before treatment. Overall, three out of six patients showed significant vision improvement. Others were sufficiently stabilized to allow follow-on surgery to restore vision. Grafting outcomes in mini-pig corneas were superior to those in human subjects, emphasizing that animal models are only predictive for patients with non-severely pathological corneas; however, for establishing parameters such as stable corneal tissue and nerve regeneration, our pig model is satisfactory. While further testing is merited, we have nevertheless shown that cell-free implants are potentially safe, efficacious options for treating high-risk patients.
... In this study, we compared in detail the safety, efficacy, and mechanism of promoting regeneration of corneal implants made from CLP-PEG to control implants made from clinically tested RHCIII-MPC in vitro, and in rabbit and mini-pig animal models. Successful testing in a simple organ system like the cornea will allow for the extension to more complex applications such as skin and heart, as we have shown with collagen after minimal modification [12][13][14]. ...
Article
Full-text available
Statement of significance: Although biomaterials comprising full-length recombinant human collagen and extracted animal collagen have been evaluated and used clinically, these macromolecules provide only a limited number of functional groups amenable to chemical modification or crosslinking and are demanding to process. Synthetic, customizable analogs that are functionally equivalent, and can be readily scaled-up are therefore very desirable for pre-clinical to clinical translation. Here, we demonstrate, using cornea regeneration as our test bed, that collagen-like-peptides conjugated to multifunctional polyethylene glycol (CLP-PEG) when grafted into mini-pigs as corneal implants were functionally equivalent to recombinant human collagen-based implants that were successfully tested in patients. We also show for the first time that these materials affected regeneration through stimulation of extracellular vesicle production by endogenous host cells that have migrated into the CLP-PEG scaffolds.
... The cells migrated toward the fibrin gel, with the total migration distance of 102.4 ? 76.1 ?m over 3 days (PEGylated) fibrin patch [208] The myocardial recruitment of c-kit+ cells was significantly higher in the group treated with the SDF-1a PEGylated fibrin patch Alginate microspheres Bone marrow- derived progenitor cells [165] Hind-limb ischemia Increased mobilization of bone marrow-derived progenitor cells and also improved recruitment of angiogenic cells expressing CXCR4 from bone marrow and local tissue hMSCs [206] Myocardial ischemia RGD-modified alginate improved cell attachment and growth and increased angiogenic growth factor expression starPEG-heparin hydrogels EPCs [146] In vitro Higher migration rates were achieved Gtn-HPA hydrogels and PCNs ...
Chapter
Over the last decade, major advances have been made in stem cell-based therapy for ischemic stroke, which is one of the leading causes of death and disability worldwide. Various stem cells from bone marrow, such as mesenchymal stem cells (MSCs), hematopoietic stem cells (HSCs), and endothelial progenitor cells (EPCs), have shown therapeutic potential for stroke. Concomitant with these exciting findings are some fundamental bottlenecks that must be overcome in order to accelerate their clinical translation, including the low survival and engraftment caused by the harsh microenvironment after transplantation. In this chapter, strategies such as gene modification, hypoxia/growth factor preconditioning, and biomaterial-based methods to improve cell survival and homing are summarized, and the potential strategies for their future application are also discussed.
... Given the powerful effects of SDF-1 in stimulating procardiogenic, pro-myogenic and pro-angiogenic responses, and its limited expression in vivo, new methods to sustain its effect in situ have been developed. They are based on the injection of collagen scaffold with synthetic microspheres containing SDF1, and have been demonstrated, so far, to enhance functional repair only in ischemic skeletal muscles [249]. ...
Article
Full-text available
The regenerative potential of tissues and organs could promote survival, extended lifespan and healthy life in multicellular organisms. Niches of adult stemness are widely distributed and lead to the anatomical and functional regeneration of the damaged organ. Conversely, muscular regeneration in mammals, and humans in particular, is very limited and not a single piece of muscle can fully regrow after a severe injury. Therefore, muscle repair after myocardial infarction is still a chimera. Recently, it has been recognized that epigenetics could play a role in tissue regrowth since it guarantees the maintenance of cellular identity in differentiated cells and, therefore, the stability of organs and tissues. The removal of these locks can shift a specific cell identity back to the stem-like one. Given the gradual loss of tissue renewal potential in the course of evolution, in the last few years many different attempts to retrieve such potential by means of cell therapy approaches have been performed in experimental models. Here we review pathways and mechanisms involved in the in vivo repair of cardiovascular muscle tissues in humans. Moreover, we address the ongoing research on mammalian cardiac muscle repair based on adult stem cell transplantation and pro-regenerative factor delivery. This latter issue, involving genetic manipulations of adult cells, paves the way for developing possible therapeutic strategies in the field of cardiovascular muscle repair.
... Many of the biomaterials developed and tested for use in the simple human cornea can be extended to use in promoting regeneration in more complex internal organs. For example, our group has been testing collagen hydrogels as a delivery system for angiogenic stem cells, and to date, it has been found that they can restore vascularization to ischaemic muscle [37,38]. Silk-based scaffolds used as regenerative templates in the cornea are also being tested as patches and scaffolds for cardiac regeneration [39]. ...
Article
The cornea is the transparent front part of the eye that transmits light to the back of the eye to generate vision. Loss of corneal transparency, if irreversible, leads to severe vision loss or blindness. For decades, corneal transplantation using human donor corneas has been the only option for treating corneal blindness. Despite recent improvement in surgical techniques, donor cornea transplantation remains plagued by risks of suboptimal optical results and visual acuity, immune rejection and eventually graft failure. Furthermore, the demand for suitable donor corneas is increasing faster than the number of donors, leaving thousands of curable patients untreated worldwide. Here, we critically review the state of the art of biomaterials for corneal regeneration. However, the lessons learned from the use of the cornea as a disease model will allow for extension of the biomaterials and techniques for regeneration of more complex organs such as the heart.
... Proteolytic degradation and reduced bioactivity of exogenous growth factors and chemokines in the chronic wound microenvironment presents a significant challenge for endogenous stem cell recruitment strategies and stem cellderived molecular therapies [52]. To address this challenge, micro-and nano-scale scaffolds and carriers have been investigated as delivery vehicles for growth factors [148][149][150][151][152][153] and conditioned media [137]. Electrospun scaffolds have been used to deliver SDF-1a for bone marrow stem cell recruitment in bone regeneration [151,152]. ...
... Electrospun scaffolds have been used to deliver SDF-1a for bone marrow stem cell recruitment in bone regeneration [151,152]. Similarly, release of SDF-1a from alginate microspheres within a collagen gel was shown to increase mobilization and homing of bone marrow progenitor cells in ischemic skeletal muscle [153]. It is easily envisioned that a similar approach could be used to obtain sustained SDF-1a or VEGF release from chronic wounds and improve endothelial progenitor homing and mobilization. ...
Chapter
Chronic wounds that do not heal with standard wound care are a growing public healthcare concern. Wound care costs associated with lower extremity ulcers, such as venous leg ulcers, pressure ulcers, and diabetic foot ulcers, place a signifi cant burden on healthcare systems and severely lower the quality of life for patients. Advanced wound care therapies are needed to promote wound closure in recalcitrant wounds. Exogenous mesenchymal stem cell delivery and endogenous bone marrow stem cell recruitment have been investigated as advanced wound therapies, and have demonstrated promising potential for enhancing wound closure in preclinical and clinical studies. The aim of this book chapter is to review the wound healing process and pathobiology of chronic wounds, and discuss the current state of stem cell therapies as advanced wound therapies. The potential role of nano- and micro-scale technologies in addressing current limitations of stem cell therapies will also be explored. © Springer International Publishing Switzerland 2016. All right reserved.