Delivery Of bFGF Research Articles

Accelerated full-thickness wound healing via sustained bFGF delivery based on a PVA/chitosan/gelatin hydrogel incorporating PCL microspheres

Herein, a hybrid hydrogel/microsphere system is introduced for accelerated wound healing by sustained release of basic fibroblast growth factor (bFGF). The hydrogel is composed of a mixture of PVA, gelatin and chitosan. The double-emulsion-solvent-evaporation method was utilized to obtain microspheres composed of PCL, as the organic phase, and PVA, as the aqueous phase. Subsequently, various in-vitro and in-vivo assays were performed to characterize the system. BSA was used to optimize the release mechanism, and encapsulation efficiency in microspheres, where a combination of 3% (w/v) PCL and 1% (w/v) PVA was found to be the optimum microsphere sample. Incorporation of microspheres within the hydrogel substrate also led to a zero-order release kinetics. Results from SEM images, also represented an average porosity of 54%, and average mean pore size of 35 ± 7 μm for the hydrogel system, and the diameter of 5 ± 2 μm for the microspheres. Moreover, in vivo study including wound healing process, and histological analysis regarding re-epithelization, angiogenesis, inflammation, fibroblast genesis and collagen formation were performed using Hematoxyline-Eosin (H&E) staining, Periodic Acid–Schiff (PAS) staining and Masson’s Trichrome staining. In-vivo results represented that sustained delivery of bFGF promoted by biocompatibility of PVA/chitosan/gelatin hydrogel, significantly contribute to accelerated wound healing.

Design and fabrication of GelMA/chitosan nanoparticles composite hydrogel for angiogenic growth factor delivery

The cellular microenvironment plays a crucial role in improving cell response and function of an engineered tissue. Scaffolds mimicking the native ECM and capable of releasing growth factors are great candidates for tissue engineering applications. Gelatin methacryloyl (GelMA) hydrogel, a photocrosslinkable biomaterial possessing tunable properties, has been widely used in tissue engineering. It has been suggested that incorporating micro/nano carriers in GelMA could provide a sustained release of growth factors. Specifically, chitosan nanoparticles can be used for growth factor delivery due to its biocompatibility, easy method of synthesis, and preventing the biomolecule from degradation. In this study, GelMA/chitosan nanoparticles composite hydrogel was developed to deliver an angiogenic growth factor (bFGF). The hydrogel was prepared by photopolymerization and its chemical and physical properties were characterized. Its degradation and swelling characteristics were also evaluated. The size of nanoparticles was evaluated and the profile of bFGF release from the hydrogel and its effect on the viability of fibroblast cells was studied. The results showed that GelMA/chitosan nanoparticles can significantly promote cell proliferation due to its biocompatible structure and providing a sustained profile of bFGF release. This hydrogel scaffold can be used for efficient delivery of bFGF in various applications and especially for angiogenesis.

Intramyocardial delivery of bFGF with a biodegradable and thermosensitive hydrogel improves angiogenesis and cardio-protection in infarcted myocardium.

Basic fibroblast growth factor (bFGF), a known angiogenic factor, may provide a potential strategy for the treatment of myocardial infarction (MI), but it is limited by a relatively short half-life. Dex-PCL-HEMA/PNIPAAm hydrogel provides a reservoir for the controlled release of growth factors. The aim of the current study was to evaluate the effects of bFGF incorporated into a Dex-PCL-HEMA/PNIPAAm hydrogel on angiogenesis and cardiac health in a rat model of acute MI, induced by coronary artery ligation. Phosphate-buffered solution (PBS group), Dex-PCL-HEMA/PNIPAAm hydrogel (Gel group), bFGF in phosphate-buffered solution (bFGF group) or bFGF in hydrogel (Gel + bFGF group) was injected into a peri-infarcted area of cardiac tissue immediately following MI. On day 30 post-surgery, cardiac function was assessed by echocardiography, apoptosis index by terminal deoxynucleotidyl transferase dUTP nick-end labeling assessment and vascular development by immunohistochemical staining. The findings demonstrated that injection of bFGF along with hydrogel induced angiogenesis, reduced collagen content, MI area and cell apoptosis and improved cardiac function compared with the injection of either bFGF or hydrogel alone. bFGF incorporated with Dex-PCL-HEMA/PNIPAAm hydrogel injection induces angiogenesis, attenuates cardiac remodeling and improves cardiac function following MI.

Accelerated Vascularization of Silk Fibroin Scaffolds Through Immobilized Basic Fibroblast Growth Factor (bFGF)

Angiogenesis of an implanted tissue is one of the most important issues in skin repairment. Porous bFGF-immobilized silk fibroin (bSF) scaffolds was fabricated by freeze drying using EDC agent crosslinking bFGF and SF with an aim of controlling bFGF delivery for the revascularization improvement. The bSF scaffolds retained a porous structure with 200～300 μm diameter and 85～91% porosity. The seeded L929 cells had notably improved growth and proliferation on bSF scaffolds, suggesting bFGF sustained release from SF scaffolds and remained bioactivity. After implantation into the skin defect of sprague-dawley (SD) rat dorsum, the bSF scaffolds revealed significantly higher wound recovery rate with complete reepithelialization and regeneration of skin appendages compared with SF scaffolds. The new vessels density and collagen deposition were also higher in bSF scaffolds after 4-week treatment, which provided the therapeutic potentials of the SF scaffolds in the regeneration of wounded tissue.

A chitin film containing basic fibroblast growth factor with a chitin-binding domain as wound dressings

Basic fibroblast growth factor (bFGF) can stimulate wound healing. However, consistent delivery of bFGF has many disadvantages. To decrease their instability and diffusible, we introduced chitin-binding domain (ChtBD) into bFGF. Two expression plasimids were constructed. The first one (named bFGF) contained bFGF (154 amino acids), the second (named ChtBD-bFGF) contained bFGF and the ChtBD (54 amino acids). ChtBD was derived from chitinase A1 (ChiA1) of Bacillus circulans WL-12. The recombinant protein ChtBD-bFGF had the same biological activity as bFGF in promoting fibroblast proliferation. Chitin powder was dissolved in 11wt% NaOH and 4wt% urea aqueous solution via the freezing/thawing method. A chitin solution was spread on a glass plate and coagulated with anhydrous alcohol. The chitin binding ability of ChtBD-bFGF was 11.4-fold higher (up to 286μg/cm2) than bFGF in vitro. The immunofluorescence data indicated that the ChtBD-bFGF@chitin film promoted cell adhesion and proliferation. The ChtBD-bFGF@chitin film and bFGF@chitin films were implanted subcutaneously. Histological analysis showed that ChtBD-bFGF promoted vascularization at the implanted site more effectively than bFGF. These results suggest that the ChtBD-bFGF@chitin film is a stabile delivery vehicle for accelerating wound healing.

Multifunctional Nanocomposite Films for Synergistic Delivery of bFGF and BMP-2.

The development of novel materials capable of delivering multiple growth factors is urgent and essential for rapid and effective tissue regeneration. In this study, a kind of composite film composed of poly-l-lysine (PLL), heparin (Hep), and Au nanoparitcles (Au nps) has been fabricated to deliver the basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) simultaneously. The films have been found to show enhanced mechanical property due to the incorporation of Au nps. They have also shown good anticoagulation activity with long activated partial thromboplastin time because of the contribution of Hep molecules. Moreover, the osteogenesis studies reveal that the loaded bFGF and BMP-2 in the composite films have a synergistic differentiation effect on mesenchymal stem cells, as indicated by alkaline phosphatase (ALP) activity assay and collagen type I (Col-I) gene expression. In contrast to the (PLL/Hep)6/BMP-2/(PLL/Au nps)6/(PLL/Hep)6 and (PLL/Hep)6/(PLL/Au nps)6/(PLL/Hep)6/bFGF films, the (PLL/Hep)6/BMP-2/(PLL/Au nps)6/(PLL/Hep)6/bFGF films have shown higher ALP activity and higher Col-I expression level. Therefore, the developed multifunctional films could be potentially used as osteoinductive coatings of biomaterials. Particularly, this simple and convenient strategy provides an effective approach for the immobilization of multiple growth factors, which may be extended to other bioactive systems for the development of novel multifunctional bioactive surfaces.

Human Basic Fibroblast Growth Factor Inhibits Tau Phosphorylation via the PI3K/Akt-GSK3β Signaling Pathway in a 6-Hydroxydopamine-Induced Model of Parkinson's Disease

Background: Basic fibroblast growth factor (bFGF) has been increasingly investigated due to its neuroprotection in neurodegenerative disorders. Because there are still no cures for any of these disorders, it is crucial to identify new therapeutic targets and screen potential drugs. The increased phosphorylation of tau at Ser³⁹⁶ leads to intracellular tau accumulation, which forms neurofibrillary tangles in Parkinson's disease (PD). In this study, neuroprotection by bFGF was observed, and the mechanisms related to its regulation of phosphorylated tau were investigated. Methods: bFGF-loaded liposome carriers were intranasally administered to rats. The neuroprotective effects of bFGF were assessed in a PD model induced by 6-hydroxydopamine (6-OHDA) in vivo and in vitro. The phosphorylation of tau was measured, and the PI3K/Akt-GSK3β signaling pathway was investigated. Results: Our study demonstrated that liposomes markedly assisted in the delivery of bFGF to the striatum and substantia nigra of rats and enhanced the neuroprotective effects of bFGF on dopaminergic neurons. bFGF treatment significantly ameliorated the behavioral deficits induced by 6-OHDA, rescued the loss of tyrosine hydroxylase-positive neurons and increased the number of Nissl bodies. bFGF reduced the phosphorylation of tau and GSK3β and increased the phosphorylation of PI3K/Akt. Conclusion: Liposomes markedly assisted in the delivery of bFGF to the brain and enhanced the neuroprotective effects of bFGF by inhibiting the phosphorylation of tau. bFGF down-regulated the phosphorylation of tau by increasing the phosphorylation of GSK3β via the PI3K/Akt signaling pathway. These findings provide a new vision of bFGF as a potential therapy for PD.

Sequential delivery of chlorhexidine acetate and bFGF from PLGA-glycol chitosan core-shell microspheres

Wound treatment should meet the challenge both of preventing infection and promoting wound healing. To design a sequential delivery system for wound healing, PLGA-glycol chitosan (GC) core-shell microspheres containing chlorhexidine acetate (CHA) at the GC shell and bFGF in the core of PLGA microspheres were fabricated using emulsion-solvent evaporation method. SEM showed that the microspheres were all spherical in shape with a smooth surface. The average size of PLGA-GC microspheres increased due to the GC coating on the surface. The results of release profiles and fluorescence images indicated that PLGA-GC microspheres had an ability to deliver drugs in sequence. The CHA was rapidly released, whereas the proteins presented a sustained release. The release behavior could be modulated by changing the GC amount. Antibacterial assay and cell proliferation tests suggested that the released CHA and bFGF retained their antimicrobial activity and bioactivity during preparation. The microspheres exhibited non-cytotoxicity against 3T3 cells and had a good biocompatibility. These results demonstrated that PLGA-GC core-shell microspheres could be a promising controlled release system of delivering drugs and proteins in sequence for wound healing.

Intranasal delivery of bFGF with nanoliposomes enhances in vivo neuroprotection and neural injury recovery in a rodent stroke model

Basic fibroblast growth factor (bFGF) may protect stroke patients from cerebral ischemia–reperfusion (I/R) injury. In this study, we report the intranasal use of novel nanoliposomes for the brain delivery of bFGF in a rat model of cerebral I/R. Compared with free bFGF, nanoliposomal therapy was able to significantly improve bFGF accumulation in brain tissues (p<0.05) including the most affected ischemic penumbra regions (e.g. hippocampus, pallium). After intranasal bFGF-nanoliposomal treatment for 3 consecutive days, functional recovery as indicated by improved neurologic deficit score and spontaneous locomotor activity was observed, and the stroke infarct volume was nearly halved (p<0.001) which persisted after 21days. These neuroprotective effects could be blocked by the PI3-K/Akt inhibitor LY294002, indicating the involvement of PI3-K/Akt activation in the therapeutic action. Overall, our results support the intranasal use of nanoliposomal bFGF as an efficient, non-invasive means to bypass the blood–brain barrier for ischemic stroke treatment.

Acceleration of skin regeneration in full-thickness burns by incorporation of bFGF-loaded alginate microspheres into a CMCS-PVA hydrogel.

Two important issues in skin tissue engineering are the vascularization and regeneration of the dermis. Basic fibroblast growth factor (bFGF) is known to promote angiogenesis and accelerate wound healing. Direct delivery of bFGF to the wound area, however, would lead to a loss of bioactivity. To this end, bFGF-loaded alginate microspheres (Ms) were fabricated and incorporated into carboxymethyl chitosan (CMCS)-poly(vinyl alcohol) (PVA) to form a composite hydrogel. Scanning electron microscopy (SEM) results indicated that the incorporation of Ms does not significantly affect the inner structure of CMCS-PVA. In an in vitro study, the release of bFGF from Ms-CMCS-PVA in a sustained manner retained higher bioactivity over a 2-week period. Full-thickness burn wounds were created in the dorsal area of rats for in vivo evaluation of skin regeneration treated with CMCS-PVA hydrogel, with and without bFGF. Compared with the control, CMCS-PVA and bFGF-CMCS-PVA groups, the bFGF/Ms-CMCS-PVA group revealed significantly faster wound recovery rates, with re-epithelialization and regeneration of the dermis. Moreover, the bFGF/Ms-CMCS-PVA group had the highest density of newly formed and mature blood vessels during the 2 mweek treatment period. The ability of the bFGF/Ms-CMCS-PVA hydrogel to accelerate wound healing in a full-thickness burn model suggests its potential for use in dermal tissue regeneration. Copyright © 2015 John Wiley & Sons, Ltd.

Repair of spinal cord injury by implantation of bFGF-incorporated HEMA-MOETACL hydrogel in rats.

There is no effective strategy for the treatment of spinal cord injury (SCI). An appropriate combination of hydrogel materials and neurotrophic factor therapy is currently thought to be a promising approach. In this study, we performed experiments to evaluate the synergic effect of implanting hydroxyl ethyl methacrylate [2-(methacryloyloxy)ethyl] trimethylammonium chloride (HEMA-MOETACL) hydrogel incorporated with basic fibroblast growth factor (bFGF) into the site of surgically induced SCI. Prior to implantation, the combined hydrogel was surrounded by an acellular vascular matrix. Sprague–Dawley rats underwent complete spinal cord transection at the T-9 level, followed by implantation of bFGF/HEMA-MOETACL 5 days after transection surgery. Our results showed that the bFGF/HEMA-MOETACL transplant provided a scaffold for the ingrowth of regenerating tissue eight weeks after implantation. Furthermore, this newly designed implant promoted both nerve tissue regeneration and functional recovery following SCI. These results indicate that HEMA-MOETACL hydrogel is a promising scaffold for intrathecal, localized and sustained delivery of bFGF to the injured spinal cord and provide evidence for the possibility that this approach may have clinical applications in the treatment of SCI.

Concomitant Retrograde Coronary Venous Infusion of Basic Fibroblast Growth Factor Enhances Engraftment and Differentiation of Bone Marrow Mesenchymal Stem Cells for Cardiac Repair after Myocardial Infarction.

Aim: Basic fibroblast growth factor (bFGF) increases the migration and viability of bone marrow mesenchymal stem cells (MSCs) in vitro. Retrograde coronary venous infusion can provide both increased regional bFGF concentrations and homogeneous cell dissemination. We determined whether retrograde delivery of bFGF enhances the potency of transplanted MSCs for cardiac repair in a canine infarct model.Methods and Results: Under hypoxic conditions, cellular migration was significantly increased in MSCs co-cultured with bFGF compared to vascular endothelial growth factor or insulin-like growth factor, and bFGF promoted MSCs differentiation into a cardiomyocyte phenotype. A canine infarct model was employed by coronary ligation. One week later, animals were subjected to retrograde infusion of combination bFGF (200ng/mL) and MSCs (1×108 cells) (n=5), MSCs (1×108 cells, n=5), bFGF (200ng/mL, n=5), or placebo (phosphate-buffered saline, n=3). Four weeks after infusion, only the bFGF+MSCs therapy exhibited significantly increased left ventricular ejection fraction (LVEF) by echocardiography (p<0.01 vs pre-infusion), and the treatment effect (delta LVEF) was greater in the bFGF+MSCs group compared to saline (7.43±1.51% versus -10.07±2.94%; p<0.001). Morphologic analysis revealed an increased infarct wall thickness in the bFGF+MSCs group compared to all others (p<0.05), accompanied by increased vascular density and reduced apoptosis. Immunofluorescence demonstrated increased cell engraftment and enhanced vascular differentiation in the bFGF+MSCs group compared to MSCs alone (p<0.05).Conclusions: Retrograde coronary venous bFGF infusion augments engraftment and differentiation capacity of transplanted MSCs, recovering cardiac function and preventing adverse remodeling. This novel combined treatment and delivery method is a promising strategy for cardiac repair after ischemic injury.

Delivery of bFGF for Tissue Engineering by Tethering to the ECM.

Delivery of growth factors to target cells is an important subject in tissue engineering. Towards that end, we have developed a growth factor-tethered extracellular matrix (ECM). Here, basic fibroblast growth factor (bFGF) was tethered to extracellular matrix noncovalently. The designed ECM was comprised of 12 repeats of the APGVGV peptide motif derived from elastin as a stable structural unit and included the well-known cell adhesive RGD peptide as an active functional unit. To bind bFGF to the ECM, an acidic amino acid-rich sequence was introduced at the C-terminus of the ECM protein. It consisted of 5 repeats of 4 aspartic acids and a serine, DDDDS. bFGF has a highly basic amino acid domain. Therefore, bFGF was tethered to the ECM protein by electrostatic interaction. Cells cultured on bFGF-tethered ECM were well attached to the ECM and induced proliferation without addition of soluble bFGF.

Transdermal bFGF delivery using low-frequency sonophoresis: An innovative potential therapy for osteoradionecrosis of jaws

Abstract Osteoradionecrosis of jaws (ORNJ) is a serious complication of radiotherapy for patients with head and neck cancer. As of yet, no universally accepted treatment exists for this chronic pathologic condition. It has been shown that ultrasound is an effective, noninvasive adjunctive therapy in ORNJ, as ultrasound can result in the increase of angiogenesis and bone production, which are essential for ORNJ healing. Recently, low-frequency ultrasound has been demonstrated to enhance the transdermal delivery of macromolecules and hydrophilic drugs (low-frequency sonophoresis, LFS). As a biological macromolecule, basic fibroblast growth factor (bFGF) also has potential osteoinductive and angiogenic properties. Herein, we present a hypothesis that LFS-mediated transdermal bFGF delivery is capable of improving the healing of ORNJ and will be a new effective adjunctive therapy to surgery. This treatment combines low-frequency ultrasound with bFGF to respectively promote vascularly compromised bone and soft tissue wound healing, and is expected to be more effective than ultrasound therapy alone.

Bladder Acellular Matrix Conjugated with Basic Fibroblast Growth Factor for Bladder Regeneration

Basic fibroblast growth factor (bFGF) plays an important role in wound repair and tissue regeneration. Considerable research has been focused on the exploration of bFGF delivery systems for maintaining efficient local concentration at the injury sites. In this study, bFGF was chemically crosslinked to the bladder acellular matrix (BAM) to create specific binding between bFGF and BAM. The BAM scaffold conjugated with bFGF (CL-BAM/bFGF) could bind more bFGF and achieve controlled release of bFGF, which promoted human fibroblasts to proliferate in vitro and accelerated cellularization and vascularization after subcutaneous implantation. Using the rat bladder reconstruction model, the CL-BAM/bFGF group showed better tissue regeneration compared with the other groups. In summary, CL-BAM/bFGF could prevent the diffusion of bFGF from BAM and maintain its activity. Thus, the scaffold conjugated with growth factor systems could be an effective way for maintaining local therapy dosage at the target site in wound repair and tissue regeneration.

Hydrogel micropattern-incorporated fibrous scaffolds capable of sequential growth factor delivery for enhanced osteogenesis of hMSCs.

In this study, we developed multi-functional biomimetic tissue engineered scaffolds that are capable of controlling the spatial locations of stem cells and releasing multiple growth factors with a controlled dose and rate of delivery. This novel scaffold was fabricated by combining electrospinning and photolithography and consisted of polycaprolactone (PCL)/gelatin fibers and poly(ethylene glycol) (PEG) hydrogel micropatterns. The utility of this system was investigated in the context of the osteogenesis of human mesenchymal stem cells (hMSCs). When hMSCs were seeded onto hydrogel-incorporated fibrous scaffolds, they selectively adhered and grew only in the fiber region due to the non-adhesiveness of the PEG hydrogel, enabling spatial positioning of hMSCs on a micrometer scale. For osteogenic differentiation of hMSCs, basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) were loaded on the fibers and within the hydrogel matrix, respectively, to enable sequential delivery of low doses of bFGF during the early stages and sustained release of BMP-2 for long periods. According to in vitro studies, hMSCs cultured on the scaffolds capable of sequential delivery of bFGF and BMP-2 showed stronger osteogenic commitment in culture than those on scaffolds without any growth factors or scaffolds with single administration of either bFGF or BMP-2 under the same conditions. The results demonstrate that hydrogel-incorporated fibrous scaffolds can provide not only biomimetic structures with micropatterned nanostructures but also a suitable biochemical environment with controlled release of multiple growth factors, which may eventually facilitate the control of stem cell fates for various regenerative therapies.

Tailored design of electrospun composite nanofibers with staged release of multiple angiogenic growth factors for chronic wound healing

The objective of this research study is to develop a collagen (Col) and hyaluronic acid (HA) inter-stacking nanofibrous skin equivalent substitute with the programmable release of multiple angiogenic growth factors (vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and endothelial growth factor (EGF)) either directly embedded in the nanofibers or encapsulated in the gelatin nanoparticles (GNs) by electrospinning technology. The delivery of EGF and bFGF in the early stage is expected to accelerate epithelialization and vasculature sprouting, while the release of PDGF and VEGF in the late stage is with the aim of inducing blood vessels maturation. The physiochemical characterizations indicate that the Col–HA–GN nanofibrous membrane possesses mechanical properties similar to human native skin. The design of a particle-in-fiber structure allows growth factors for slow controlled release up to 1month. Cultured on biodegradable Col–HA membrane with four kinds of growth factors (Col–HA w/4GF), endothelial cells not only increase in growth rate but also form a better network with a thread-like tubular structure. The therapeutic effect of Col–HA w/4GF membrane on streptozotocin (STZ)-induced diabetic rats reveals an accelerated wound closure rate, together with elevated collagen deposition and enhanced maturation of vessels, as revealed by Masson’s trichrome stain and immunohistochemical analysis, respectively. From the above, the electrospun Col–HA–GN composite nanofibrous skin substitute with a stage-wise release pattern of multiple angiogenic factors could be a promising bioengineered construct for chronic wound healing in skin tissue regeneration.

Functional and pathological improvements of the hearts in diabetes model by the combined therapy of bFGF-loaded nanoparticles with ultrasound-targeted microbubble destruction

Diabetic cardiomyopathy (DCM) is the leading cause of morbidity and mortality among the diabetic patients and currently there is no effective means to reverse its pathological progress. Basic fibroblast growth factor (bFGF) has shown promise as a molecular therapy for DCM, but its delivery is inefficient and non-specific. In the present study, a therapy combining nanoparticle (NP) carrier and ultrasound-targeted microbubble destruction (UTMD) was reported the first time for bFGF delivery to the heart of diabetic rats. bFGF-loaded NP (bFGF-NP) were prepared with Poloxamer 188-grafted heparin copolymer using water-in-water technique, and the morphology, encapsulation efficiency, and bioactivity of bFGF-NP were studied. The cellular uptake and cytotoxicity of bFGF-NP were evaluated with primary cultures of the left ventricular (LV) cardiomyocytes in vitro. Therapeutic effects of bFGF-NP/UTMD on the heart of DCM rats were studied by measuring LV systolic and diastolic functions, hemodynamic characteristics and indicators of cardiac remodeling including myocardial collagen volume fraction and capillary density. Results demonstrated that bFGF-NP showed good round morphology, efficient bFGF encapsulation and stable bioactivity of bFGF in vitro. bFGF-NP/UTMD combined treatment significantly enhanced the efficiency of bFGF cellular uptake (P<0.05) without obvious cytotoxicity. Significant improvements (P<0.05) in both cardiac functions and tissue morphology in the DCM rats were observed in bFGF-NP/UTMD group. These were not achievable using free bFGF, bFGF-NP or UTMD treatment alone. Our results show that combining a non-viral vector with UTMD technique is an effective strategy to deliver bFGF to the heart, and the resulting growth factor therapy has demonstrated potential to reverse the progress of DCM by restoring the cardiac functions and even the structure of damaged cardiac tissues.

Therapeutic site selection is important for the successful development of collateral vessels

Induction of collateral development to improve tissue perfusion is a promising approach for the treatment of arterial occlusive diseases. Several growth factors and cells have been reported to increase collateral circulation; however, the appropriate site for the delivery of these factors and cells is unclear. In this study, we identified the delivery site for growth factor in a rabbit model of limb ischemia and evaluated whether specific delivery of basic fibroblast growth factor (bFGF) to this site enhanced collateral augmentation. The left femoral artery of Japanese white rabbits was excised to induce limb ischemia. Twenty-eight days thereafter, angiograms were obtained to identify the typical pattern of collateral development in this model. Subsequently, bFGF (100 μg) was selectively injected into the left coccygeofemoral muscle (coccygeo group) or adductor muscle (adductor group), major thigh muscles in proximity. Collateral development was evaluated at 28 days after injection, and its mechanism was assessed by immunologic and morphometric analyses of muscle samples. Angiographic evaluation of this model revealed that after femoral artery excision, collateral vessels generally developed in the left coccygeofemoral muscle, whereas few collateral vessels were detected in the left adductor muscle. At 28 days after injection, calf blood pressure ratio, defined as left pressure to right pressure, was significantly higher in the coccygeo group than in the adductor group (0.85 ± 0.05 vs 0.69 ± 0.05, respectively; P < .01). Similar results were observed in blood flow through the internal iliac artery (resting: 24.6 ± 6.1 vs 17.4 ± 8.0 mL/min, P < .01; maximum: 47.4 ± 12.3 vs 33.2 ± 10.7 mL/min, P < .01) and in the angiographic score (0.67 ± 0.13 vs 0.39 ± 0.11; P < .01). Immunologic analyses of the coccygeofemoral muscle at day 3 showed marked expressions of Ki-67, monocyte chemotactic protein 1, and FGF receptor 1 in the coccygeo group compared with the adductor group. Morphometric analyses of the same muscle at day 14 also revealed that collateral vessel density and wall thickness were significantly increased in the coccygeal group compared with the adductor group. These findings demonstrated that selective bFGF delivery to the coccygeofemoral muscle markedly improved collateral development and limb perfusion compared with delivery to the adductor muscle, suggesting that site selection is important in increasing therapeutic efficacy.

Intramyocardial Injection of a Synthetic Hydrogel with Delivery of bFGF and IGF1 in a Rat Model of Ischemic Cardiomyopathy

It is increasingly appreciated that the properties of a biomaterial used in intramyocardial injection therapy influence the outcomes of infarcted hearts that are treated. In this report the extended in vivo efficacy of a thermally responsive material that can deliver dual growth factors while providing a slow degradation time and high mechanical stiffness is examined. Copolymers consisting of N-isopropylacrylamide, 2-hydroxyethyl methacrylate, and degradable methacrylate polylactide were synthesized. The release of bioactive basic fibroblast growth factor (bFGF) and insulin-like growth factor 1 (IGF1) from the gel and loaded poly(lactide-co-glycolide) microparticles was assessed. Hydrogel with or without loaded growth factors was injected into 2 week-old infarcts in Lewis rats and animals were followed for 16 weeks. The hydrogel released bioactive bFGF and IGF1 as shown by mitogenic effects on rat smooth muscle cells in vitro. Cardiac function and geometry were improved for 16 weeks after hydrogel injection compared to saline injection. Despite demonstrating that left ventricular levels of bFGF and IGF1 were elevated for two weeks after injection of growth factor loaded gels, both functional and histological assessment showed no added benefit to inclusion of these proteins. This result points to the complexity of designing appropriate materials for this application and suggests that the nature of the material alone, without exogenous growth factors, has a direct ability to influence cardiac remodeling.