Stromal Cell-derived Factor-1 Delivery Research Articles

Stromal cell-derived factor loaded co-electrospun hydrophilic/hydrophobic bicomponent membranes for wound protection and healing.

Chronic wounds are one of the key concerns for people with diabetes, frequently leading to infections and non-healing ulcers, and finally resulting in the amputation of limbs/organs. Stromal cell-derived factor 1 (SDF1) is a major chemokine that plays a significant role in tissue repair, vascularization, and wound healing. However, the long-term sustained delivery of SDF1 in a chronic wound environment is a great challenge. In order to facilitate the sustained release of SDF1 in diabetic wounds, it could be incorporated into wound-healing patches. Herein, we report the fabrication of a hydrophilic/hydrophobic bicomponent fiber-based membrane, where SDF1 was encapsulated inside hydrophilic fibers, and its applicability in wound healing. A co-electrospinning technique was employed for the fabrication of polymeric membranes where PVA and PCL form the hydrophilic and hydrophobic components, respectively. Morphological analysis of the developed membranes was conducted via scanning electron microscopy (SEM). The mechanical strength of the membranes was investigated via uniaxial tensile testing. The water uptake capacity of the membranes was also determined to understand the hydrophilicity and exudate uptake capacity of the membranes. To understand the proliferation, viability, and migration of skin-specific cells in the presence of SDF1-loaded membranes, in vitro cell culture experiments were carried out using fibroblasts, keratinocytes, and endothelial cells. The results showed the excellent porous morphology of the developed membranes with distinguishable differences in fiber diameters for the PVA and PCL fibers. The developed membranes possessed enough mechanical strength for use as wound-healing membranes. The co-electrospun membranes showed good exudate uptake capacity. The controlled and extended delivery of SDF1 from the developed membranes was observed over a prolonged period. The SDF1-loaded membranes showed enhanced cell proliferation, cell viability, and cell migration. These biocompatible and biodegradable SDF1-loaded bicomponent membranes with excellent exudate uptake capacity, and cell proliferation and cell migration properties can be exploited as a novel wound-dressing membrane aimed at chronic diabetic wounds.

A LbL-Assembled Bioactive Coating Modified Nanofibrous Membrane for Rapid Tendon-Bone Healing in ACL Reconstruction.

IntroductionIn anterior cruciate ligament (ACL) reconstruction, hamstring tendon autograft is a well-accepted surgical choice as an alternative ACL graft. But the main disadvantage of autograft is its inefficient healing with host bone-tunnel which will leading to surgery failure.MethodsA biomimetic nanofibrous membrane for tendon-bone integration is fabricated in this work, which is composed of polycaprolactone (PCL) electrospinning membrane and chitosan/hyaluronic acid (CS/HA) multilayers film.ResultsBy using layer-by-layer (LbL) self-assembly this functional CS/HA multilayer films are deposited on the surface of PCL nanofiber to enable the local delivery of stromal cell-derived factor-1 α (SDF-1α) and bone morphogenetic protein-2 (BMP-2) in tendon-bone interface. This membrane can promote cell proliferation and recruitment, as well as inducing the osteogenic differentiation and recruitment of BMSCs.ConclusionFurther in vivo studies demonstrate that to wrap the tendon autograft using the membrane may afford superior tendon-bone integration and inhibit scar tissue formation in a rabbit ACL reconstruction model. More importantly, the biomechanical properties of the tendon-bone interface have been improved. This study shows that this biomimetic nanofibrous membrane is effective for improving tendon-bone healing after ACL reconstruction surgery.

Bone Targeted Delivery of SDF-1 via Alendronate Functionalized Nanoparticles in Guiding Stem Cell Migration.

Stem cells are well-known for their great capacity for tissue regeneration. This provides a promising source for cell-based therapies in treating various bone degenerative disorders. However, the major hurdles for their application in transplantation are the poor bone marrow homing and engraftment efficiencies. Stromal cell-derived factor 1 (SDF-1) has been identified as a major stem cell homing factor. With the aims of bone targeted SDF-1 delivery and regulating MSCs migration, alendronate modified liposomal nanoparticles (Aln-Lipo) carrying SDF-1 gene were developed in this study. Alendronate modification significantly increased the mineral binding affinity of liposomes, and facilitated the gene delivery to osteoblastic cells. Up-regulated SDF-1 expression in osteoblasts triggered MSCs migration. Systemic infusion of Aln-Lipo-SDF-1 with fluorescence labeling in mice showed the accumulation in osseous tissue by biophotonic imaging. Corresponding to the delivered SDF-1, the transplanted GFP+ MSCs were attracted to bone marrow and contributed to bone regeneration. This study may provide a useful technique in regulating stem cell migration.

The potential of stromal cell-derived factor-1 delivery using a collagen membrane for bone regeneration

Stromal cell-derived factor-1 (SDF-1) is a cytokine that is important in stem and progenitor cell recruitment in tissue repair after injury. Regenerative procedures using collagen membranes (CMs) are presently well established in periodontal and implant dentistry. The objective of this study is to test the subsequent effects of the released SDF-1 from a CM on bone regeneration compared to platelet-derived growth factor (PDGF) in vitro and in vivo. For in vitro studies, cell proliferation, alkaline phosphatase activity, and osteoblastic differentiation marker genes were assessed after MC3T3-E1 mouse preosteoblasts were cultured with CMs containing factors. In vivo effects were investigated by placement of CMs containing SDF-1 or PDGF using a rat mandibular bone defect model. At 4 weeks after the surgery, the new bone formation was measured using micro-computed tomography (µCT) and histological analysis. The results of in vitro studies revealed that CM delivery of SDF-1 significantly induced cell proliferation, ALP activity, and gene expression of all osteogenic markers compared to the CM alone or control, similar to PDGF. Quantitative and qualitative µCT analysis for volume of new bone formation and the percentage of new bone area showed that SDF-1-treated groups significantly increased and accelerated bone regeneration compared to control and CM alone. The enhancement of bone formation in SDF-1-treated animals was dose-dependent and with levels similar to those measured with PDGF. These results suggest that a CM with SDF-1 may be a great candidate for growth factor delivery that could be a substitute for PDGF in clinical procedures where bone regeneration is necessary.

Therapeutic Delivery of Stromal Cell-Derived Factor-1 for Injury Repair

Stromal cell-derived growth factor-1 (SDF1) is a chemokine that is over-expressed at sites of injury and is believed to play an important role in wound repair. At the cellular level, SDF1 regulates the mobilization and trafficking of endothelial progenitors that originate in the bone marrow and functionally contribute to neovascularization and angiogenesis in the wound. Consequently, SDF1 is a potentially interesting therapeutic with the potential to enhance these processes in acute and chronic injuries that otherwise tend to heal poorly, such as spinal cord injury, stroke, myocardial infarction, diabetic skin wounds and acute burns. However, the therapeutic usefulness of SDF1, as many other similar peptide-based growth factors and chemokines, is severely limited due to its short in vivo half-life, as it is rapidly degraded by proteases, which are typically very abundant at the wound site. Several studies have reported methodologies to increase SDF1 in vivo stability by mutating the protease cleavage sites of the molecule. Another approach has been to incorporate the chemokine into biomaterials that shield it from degradation. Yet another approach would be to develop a system that is inherently stable and could be combined with these aforementioned strategies. For example, self-assembled nanoparticles could shield SDF1 (or one of its forms engineered to be more resistant to proteolysis) from proteolysis and then be incorporated into suitable biomaterials. Nanotechnology-based delivery systems have however been used to a very limited extent for SDF1. This paper aims to provide a summary of the various stabilization and delivery methods available for SDF1, some of which have been already used, as well as others that have been used with other bioactive peptides, but would be potentially applicable to SDF1.

Therapeutic Delivery of Stromal Cell-Derived Factor-1 for Injury Repair

Stromal cell-derived growth factor-1 (SDF1) is a chemokine that is over-expressed at sites of injury and is believed to play an important role in wound repair. At the cellular level, SDF1 regulates the mobilization and trafficking of endothelial progenitors that originate in the bone marrow and functionally contribute to neovascularization and angiogenesis in the wound. Consequently, SDF1 is a potentially interesting therapeutic with the potential to enhance these processes in acute and chronic injuries that otherwise tend to heal poorly, such as spinal cord injury, stroke, myocardial infarction, diabetic skin wounds and acute burns. However, the therapeutic usefulness of SDF1, as many other similar peptide-based growth factors and chemokines, is severely limited due to its short in vivo half-life, as it is rapidly degraded by proteases, which are typically very abundant at the wound site. Several studies have reported methodologies to increase SDF1 in vivo stability by mutating the protease cleavage site...

The effect of hyaluronan-based delivery of stromal cell-derived factor-1 on the recruitment of MSCs in degenerating intervertebral discs

Intervertebral disc (IVD) degeneration is the leading cause of low back pain and disability in the active population. Transplantation of mesenchymal stem cells (MSCs) in a hydrogel carrier can induce regenerative effects in degenerated IVDs. Moreover, it was found that degenerative discs release chemoattractants effective in MSC recruitment. Based on these findings, we hypothesized that an injectable hydrogel that can enhance the number of migrated MSCs in the IVD and provide a suitable matrix for their survival and differentiation would be ideal. The purpose of this study was to evaluate the potential of a thermoreversible hyaluronan-poly(N-isopropylacrylamide) (HAP) hydrogel as chemoattractant delivery system to recruit human MSCs in degenerative IVDs. The results demonstrate that HAP hydrogels containing stromal cell derived factor-1 (SDF-1) significantly increased the number of MSCs migrating into nucleotomized discs compared with discs treated with only HAP or SDF-1 in solution. HAP hydrogels releasing SDF-1 enhanced both the number of recruited cells and their migration distance in the IVD tissue. Furthermore, this phenomenon was dependent on MSC donor age. In conclusion, HAP SDF-1 is effective for the recruitment of stem cells in the IVD, thus opening new possibilities for the development of regenerative therapies based on endogenous cell migration.

Stromal Cell-Derived Factor-1 Delivery System: A New Approach for the Recruitment of Mesenchymal Stem Cells in Degenerating Intervertebral Disc

IntroductionIntervertebral disc (IVD) degeneration is a common pathology recognized nowadays as the major cause for low back pain. Current treatments still cannot address the underlying problem of ...

Modulation of Stromal Cell-Derived Factor-1/CXC Chemokine Receptor 4 Axis Enhances rhBMP-2-Induced Ectopic Bone Formation

Enhancement of in vivo mobilization and homing of endogenous mesenchymal stem cells (MSCs) to an injury site is an innovative strategy for improvement of bone tissue engineering and repair. The present study was designed to determine whether mobilization by AMD3100 and/or local homing by delivery of stromal cell-derived factor-1 (SDF-1) enhances recombinant human bone morphogenetic protein-2 (rhBMP-2) induced ectopic bone formation in an established rat model. Rats received an injection of either saline or AMD3100 treatment 1 h before harvesting of bone marrow for in vitro colony-forming unit-fibroblasts (CFU-F) culture or the in vivo subcutaneous implantation of absorbable collagen sponges (ACSs) loaded with saline, recombinant human bone morphogenetic protein-2 (rhBMP-2), SDF-1, or the combination of SDF-1 and rhBMP-2. AMD3100 treatment resulted in a significant decrease in CFU-F number, compared with saline, which confirmed that a single systemic AMD3100 treatment rapidly mobilized MSCs from the bone marrow. At 28 and 56 days, bone formation in the explanted ACS was assessed by microcomputed tomography (μCT) and histology. At 28 days, AMD3100 and/or SDF-1 had no statistically significant effect on bone volume (BV) or bone mineral content (BMC), but histology revealed more active bone formation with treatment of AMD3100, loading of SDF-1, or the combination of both AMD3100 and SDF-1, compared with saline-treated rhBMP-2 loaded ACS. At 56 days, the addition of AMD3100 treatment, loading of SDF-1, or the combination of both resulted in a statistically significant stimulatory effect on BV and BMC, compared with the saline-treated rhBMP-2 loaded ACS. Histology of the 56-day ACS were consistent with the μCT analysis, exhibiting more mature and mineralized bone formation with AMD3100 treatment, SDF-1 loading, or the combination of both, compared with the saline-treated rhBMP-2 loaded ACS. The present study is the first that provides evidence of the efficacy of AMD3100 and SDF-1 treatment to stimulate trafficking of MSCs to an ectopic implant site, in order to ultimately enhance rhBMP-2 induced long-term bone formation.

Vascular Gene Transfer of SDF-1 Promotes Endothelial Progenitor Cell Engraftment and Enhances Angiogenesis in Ischemic Muscle

Gene therapy approaches to enhance endothelial progenitor cell (EPC) homing may augment cell engraftment to ischemic tissue and lead to a greater therapeutic response. Therefore, we assessed the effects of ultrasound-mediated (UM) transfection of the chemokine stromal cell-derived factor-1 (SDF-1) on homing and engraftment of intravenously administered EPCs and the subsequent angiogenic response in chronically ischemic skeletal muscle. Bone marrow-derived EPCs were isolated from donor Fisher 344 rats, cultured and labeled in preparation for injection into recipient animals via a jugular vein. Using a model of chronic hindlimb ischemia in rats, we demonstrated that UM destruction of intravenous carrier microbubbles loaded with SDF-1 plasmid DNA resulted in targeted transfection of the vascular endothelium within ischemic muscle and greater local engraftment of EPCs. The combination of SDF-1gene therapy and EPCs lead to the greatest increase in tissue perfusion and microvascular density within ischemic muscle, compared to no treatment or either monotherapy alone. Our results demonstrate that UM transfection of SDF-1 improves EPC targeting to chronically ischemic tissue, enhancing vascular engraftment and leading to a more robust neovascularization response.

Stromal cell-derived factor-1 (SDF-1): homing factor for engineered regenerative medicine

Introduction: Stromal cell-derived factor-1α (SDF-1) is a chemokine that plays a major role in cell trafficking and homing of CD34+ stem cells. Studies employing SDF-1/CXCR4 have demonstrated its therapeutic potential in tissue engineering. During injury, cells from the injured organ highly express SDF-1, which causes an elevation of localized SDF-1 levels. This leads to recruitment and retention of circulating CD34+ progenitor cells at the injury site via chemotactic attraction toward a gradient of SDF-1. The general approaches for SDF-1 introduction in tissue engineering are direct protein incorporation into scaffolds and transplantation of SDF-1-overexpressing cells and both methods are successful in improving the regeneration of the damaged tissue/organ.Areas covered: The mechanisms of SDF-1-mediated homing via CXCR4 receptor and the success of SDF-1-based medical applications in mesenchymal stem cell (MSC) homing as well as areas such as therapeutic angiogenesis, wound healing and neuronal and liver regeneration.Expert opinion: Current SDF-1 delivery designs and platforms hold much room for improvement. Regardless of the different techniques of SDF-1 introduction, they have proved to be effective in recruitment of various stem/progenitor cells. The pursuit of SDF-1-related regenerative medicine has already begun. It is thus conceivable that its usage in the clinical setting will be a reality in the near future.

Continuous Delivery of Stromal Cell-Derived Factor-1 from Alginate Scaffolds Accelerates Wound Healing

Proper wound diagnosis and management is an increasingly important clinical challenge and is a large and growing unmet need. Pressure ulcers, hard-to-heal wounds, and problematic surgical incisions are emerging at increasing frequencies. At present, the wound-healing industry is experiencing a paradigm shift towards innovative treatments that exploit nanotechnology, biomaterials, and biologics. Our study utilized an alginate hydrogel patch to deliver stromal cell-derived factor-1 (SDF-1), a naturally occurring chemokine that is rapidly overexpressed in response to tissue injury, to assess the potential effects SDF-1 therapy on wound closure rates and scar formation. Alginate patches were loaded with either purified recombinant human SDF-1 protein or plasmid expressing SDF-1 and the kinetics of SDF-1 release were measured both in vitro and in vivo in mice. Our studies demonstrate that although SDF-1 plasmid- and protein-loaded patches were able to release therapeutic product over hours to days, SDF-1 protein was released faster (in vivo K(d) 0.55 days) than SDF-1 plasmid (in vivo K(d) 3.67 days). We hypothesized that chronic SDF-1 delivery would be more effective in accelerating the rate of dermal wound closure in Yorkshire pigs with acute surgical wounds, a model that closely mimics human wound healing. Wounds treated with SDF-1 protein (n = 10) and plasmid (n = 6) loaded patches healed faster than sham (n = 4) or control (n = 4). At day 9, SDF-1-treated wounds significantly accelerated wound closure (55.0 +/- 14.3% healed) compared to nontreated controls (8.2 +/- 6.0%, p < 0.05). Furthermore, 38% of SDF-1-treated wounds were fully healed at day 9 (vs. none in controls) with very little evidence of scarring. These data suggest that patch-mediated SDF-1 delivery may ultimately provide a novel therapy for accelerating healing and reducing scarring in clinical wounds.

Abstract 1841: Stromal Cell Derived Factor-1 Increases Capillary Density But Does Not Contribute To Cardiomyocyte Replacement After Experimental Myocardial Infarction

Background. The mechanisms by which regenerative therapies improve cardiac function are incompletely defined. Numerous laboratories have demonstrated that the stem cell chemoattractant Stromal cell derived factor-1 (SDF-1) improves cardiac function after myocardial infarction (MI). This study used a genetic fate-mapping approach to ask the question: Is the beneficial effect of SDF-1 delivery due to cardiomyocyte regeneration, increased capillary density, or both? Methods. We used a genetic fate-mapping system that allows “pulse-chase” studies of cardiomyocyte turnover in mice. We crossed an inducible cardiomyocyte-specific Mer-Cre-Mer transgenic mouse with Z/EG reporter mice. Using a high-efficiency 4-OH-tamoxifen protocol, we then induced Cre recombination and expression of GFP in cardiomyocytes only. SDF-1(S4V), a protease-resistant form of SDF-1, was delivered with nanofibers after coronary ligation. Results. The percentage of pulse-labeled GFP+ cardiomyocytes was 81±4% (n=6) in sham-operated mice, as anticipated with this system. GFP+ cardiomyocytes were 60±5% and 69±4% (n=11) respectively at MI border and MI remote areas of the control nanofiber group, consistent with our previous study and suggesting a significant stem/precursor cell contribution to cardiomyocyte replacement after injury (P&lt;0.0001). GFP+ cardiomyocytes were 65±9% and 76±6% (n=10) respectively at MI border and MI remote areas of the SDF-1(S4V)-RAD group (p=ns vs nanofiber control group), indicating no significantly increase in cardiomyocyte refreshment attributable to SDF-1. However, capillary density increased from 204.7 ± 10.1/mm2 in the nanofiber control group to 308.9 ± 21.9/mm2 in SDF-1(S4V)-RAD + nanofiber group (p =0.0003). Conclusion. Using genetic “pulse-chase” fate mapping, these data indicate that the stem cell chemoattractant SDF-1 does not induce measurable adult mammalian cardiomyocyte replacement by stem/precursor cells following injury. However, SDF-1 significantly increases myocardial capillary density, suggesting that increased angiogenesis but not cardiogenesis is responsible for the beneficial effects of SDF-1 on cardiac function.

Cell Guidance in Tissue Engineering: SDF-1 Mediates Site-Directed Homing of Mesenchymal Stem Cells within Three-Dimensional Polycaprolactone Scaffolds

Cell guidance is a new tissue engineering concept aimed at total in vivo tissue engineering without the need for cell seeding. This technique aims to create a biomimetic environment through constant delivery of cytokines to different areas of an implanted scaffold, such that site-specific homing of cells can be achieved. In this study, expression of CXCR4 on mesenchymal stem cells (MSCs) was characterized by immunohistochemistry and flow cytometry, subsequent to which chemotaxis toward stromal cell-derived factor 1 (SDF-1) was demonstrated. In a subsequent three-dimensional in vitro study, MSCs were shown to migrate within a polycaprolactone scaffold in response to SDF-1, such that polarized tissue formation could be achieved. A customized cytokine microdelivery system comprising a reservoir housing system and microneedle apparatus was fabricated to ensure constant delivery of SDF-1 to the scaffold. Following on this experiment, we demonstrated in an in vivo rat bone tissue engineering model that a cytokine combination consisting of vascular endothelial growth factor, SDF-1, and bone morphogenetic protein-6 delivered at 10-day intervals through the microneedle apparatus could lead to tissue formation through migrating cell fronts, with evidence of angiogenesis and vascularization without the need for cell seeding on scaffolds prior to implantation. In summary, cell guidance offers an advancement in cellular methodology for tissue engineering, and promises a novel, minimally invasive option for tissue regeneration.

Abstract 2897: Targeting Engraftment of Endothelial Progenitor Cells to Ischemic Tissue by Ultrasound-mediated Transfection of Stromal Cell Derived Factor-1

The homing of endothelial progenitor cells (EPC) to sites of ischemic injury is critical to successful neovascularization. We hypothesize that ultrasound-mediated (UM) transfection of stromal-cell derived factor-1 (SDF-1) would enhance engraftment of exogenously administered EPCs and improve neovascularization in a rat model of chronic hindlimb ischemia. Methods: Bone-marrow derived EPCs were isolated from donor F344 rats, cultured for 7 days, labelled with CMTMR and injected (1 x 10 6 ) into recipient animals via a jugular vein. Unilateral hindlimb ischemia was created by iliac artery ligation in 32 rats. At day 14 post ligation, microvascular blood volume (MBV) and blood flow (MBF) in the hindlimb muscles were assessed by contrast-enhanced ultrasound (CEU). Rats were assigned to 4 treatment groups: control untreated animals, EPCs alone, UM delivery of SDF-1 plasmid (500 μg DNA + 1x10 9 cationic microbubbles), and both UM delivery of SDF-1 + EPCs (n=8 per group). Perfusion was re-assessed at day 28. EPC engraftment was assessed using fluorescent microscopy. Circulating exogenous EPC numbers were determined by FACS at various time-points post injection. Results: Prior to EPC delivery, normalized MBV and MBF in ischemic muscle were similarly reduced in all groups. Control animals showed no changes in perfusion over time. By day 28, EPC treated animals had a significant increase in normalized MBV (1.04±0.24 vs 0.67±0.22, p&lt;0.001), without significant improvements in MBF (0.44±0.13 vs 0.33±0.15, p=NS), while SDF-1/EPC treated animals had significant improvement in both normalized MBV (1.33±0.51 vs 0.67±0.22, p&lt;0.001), and MBF (0.55±0.26 vs 0.33±0.15, p&lt;0.001). Maximal exogenous circulating EPCs could be detected at 72 hours post injection. Fluorescent microscopy showed little to no CMTMR labelled cells in the non-ischemic hindlimb in all groups. In comparison, a rich population of cells was found in the ischemic hindlimb of both the SDF-1/EPC and EPC treated animals, with the SDF-1/EPC animals demonstrating the greatest density of EPCs. Conclusions: Ultrasound-mediated transfection of SDF-1 improves intravenous EPC targeting, enhancing EPC engraftment into chronically ischemic tissue and leading to greater neovascularization response.