Release Of Fibroblast Growth Factor Research Articles

Fibroblast Growth Factor-Impregnated Collagen-Gelatin Sponge Improves Keratinocyte Sheet Survival.

Commercially available cultured epithelial keratinocyte sheets (KSs) have played an essential role in wound healing over the past four decades. Despite the initial uptake by the dermal elements, the survival rate of KS on the dermis-like tissue generated by conventional artificial dermis (AD) is low, making this method unsuitable for standard treatments. Therefore, an innovative AD such as collagen-gelatin sponge (CGS) that maintains the release of human recombinant basic fibroblast growth factor (bFGF) may promote wound healing. In this study, we examined whether combination therapy with KSs and CGS with bFGF (bFGF-CGS) could enhance KS survival by heterologous grafting by transplantation of human-derived KSs in an athymic nude rat wound model of staged skin reconstruction. The CGSs were implanted into skin defect wounds on athymic nude rats, which were then divided into two experimental groups: the bFGF group (CGSs containing bFGF, n = 8) and the control group (CGSs with saline, n = 8). Two weeks after implantation, human epithelial cell-derived KSs were grafted onto the dermis-like tissue, followed by assessment of the survival and morphology at 1 week later using digital imaging, histology (hematoxylin and eosin and Masson's trichrome staining), immunohistology (von Willebrand factor), immunohistochemistry (cytokeratin 1-5-6, Ki-67), and immunofluorescence (collagen IV, pan-cytokeratins) analyses. The bFGF group showed a significantly higher KS survival area (86 ± 58 mm2 vs. 32 ± 22 mm2; p < 0.05) and increased epidermal thickness (158 ± 66 μm vs. 86 ± 40 μm; p < 0.05) compared with the control group, along with higher dermis-like tissue regeneration, neovascularization, epidermal maturation, and basement membrane development. These results indicate that the survival rate of KSs in the dermis-like tissue formed by bFGF-CGS was significantly increased. Therefore, combination treatment of bFGF-CGS and KSs shows potential for full-thickness skin defect reconstruction in clinical situations. Impact statement This study highlights how using a combination of cultures, keratinocyte sheets, and collagen-gelatin sponge containing basic fibroblast growth factors can significantly improve cell survival in athymic nude rats with staged skin reconstruction. Our study makes a significant contribution to the literature because it highlights a novel and improved strategy for treating a very common condition such as skin wounds arising from many conditions. Clinical translation of this study may be useful for treating skin wounds.

Photocrosslinked gelatin hydrogel improves wound healing and skin flap survival by the sustained release of basic fibroblast growth factor

Biomaterials traditionally used for wound healing can act as a temporary barrier to halt bleeding, prevent infection, and enhance regeneration. Hydrogels are among the best candidates for wound healing owing to their moisture retention and drug-releasing properties. Photo-polymerization using visible light irradiation is a promising method for hydrogel preparation since it can easily control spatiotemporal reaction kinetics and rapidly induce a single-step reaction under mild conditions. In this study, photocrosslinked gelatin hydrogels were imparted with properties namely fast wound adherence, strong wet tissue surface adhesion, greater biocompatibility, long-term bFGF release, and importantly, ease of use through the modification and combination of natural bio-macromolecules. The production of a gelatin hydrogel made of natural gelatin (which is superior to chemically modified gelatin), crosslinked by visible light, which is more desirable than UV light irradiation, will enable its prolonged application to uneven wound surfaces. This is due to its flexible shape, along with the administration of cell growth factors, such as bFGF, for tissue regeneration. Further, the sustained release of bFGF enhances wound healing and skin flap survival. The photocrosslinking gelatin hydrogel designed in this study is a potential candidate to enhance wound healing and better skin flap survival.

Effect of Fascia Implantation and Controlled Release of Basic Fibroblast Growth Factor for Muscle Atrophy in Rat Laryngeal Paralysis.

To improve lateral thyroarytenoid (TA) muscle atrophy after laryngeal paralysis, reconstruction of the vascular network of the atrophied muscle is necessary. We therefore evaluated whether the controlled release of basic fibroblast growth factor (bFGF) with autologous fascia implantation could affect vascular reconstruction in the lateral TA muscle. Animal experiment. Laboratory. Unilateral laryngeal paralysis was induced in 20 rats. The rats were implanted with autologous fascia and a gelatin hydrogel sheet with or without 1 µg of bFGF (fascia and bFGF + fascia groups; n = 5 each) and with only a gelatin hydrogel sheet with bFGF (bFGF group: n = 5). Another group remained untreated (n = 5) at 4 months after paralysis. At 3 months since transplantation, intra- and intergroup comparisons of the muscle volumes and total area of blood vessels in the lateral TA muscle were performed. When compared with the untreated group, the bFGF + fascia group showed a significant increase in muscle volume (P =.0008) and vascular area (P =.0002) in the lateral TA muscle, whereas the other 2 treated groups demonstrated an insufficient effect. bFGF + fascia implantation showed histologic improvement in severe laryngeal paralysis. We demonstrated that the decrease in lateral TA muscle mass after paralysis might be countered by the reconstruction of the vascular network. Our findings indicate that hypovascular and denervated areas of the laryngeal muscle can be regenerated by the implantation of growth factors and scaffolds with surgical stress. 5.

Release of basic fibroblast growth factor from acoustically-responsive scaffolds promotes therapeutic angiogenesis in the hind limb ischemia model

Pro-angiogenic growth factors have been studied as potential therapeutics for cardiovascular diseases like critical limb ischemia (CLI). However, the translation of these factors has remained a challenge, in part, due to problems associated with safe and effective delivery. Here, we describe a hydrogel-based delivery system for growth factors where release is modulated by focused ultrasound (FUS), specifically a mechanism termed acoustic droplet vaporization. With these fibrin-based, acoustically-responsive scaffolds (ARSs), release of a growth factor is non-invasively and spatiotemporally-controlled in an on-demand manner using non-thermal FUS. In vitro studies demonstrated sustained release of basic fibroblast growth factor (bFGF) from the ARSs using repeated applications of FUS. In in vivo studies, ARSs containing bFGF were implanted in mice following induction of hind limb ischemia, a preclinical model of CLI. During the 4-week study, mice in the ARS + FUS group longitudinally exhibited significantly more perfusion and less visible necrosis compared to other experimental groups. Additionally, significantly greater angiogenesis and less fibrosis were observed for the ARS + FUS group. Overall, these results highlight a promising, FUS-based method of delivering a pro-angiogenic growth factor for stimulating angiogenesis and reperfusion in a cardiovascular disease model. More broadly, these results could be used to personalize the delivery of therapeutics in different regenerative applications by actively controlling the release of a growth factor.

Polyelectrolyte multilayer composite coating on 316 L stainless steel for controlled release of dual growth factors accelerating restoration of bone defects

A composite coating of polyelectrolyte multilayers (PEMs) consisting of collagen, a chitosan barrier, and poly-γ-glutamic acid was fabricated using a spin coating technique to investigate and overcome the limited osseointegration capacity of 316 L stainless steel (316 L SS). To further enhance the biocompatibility, bone morphogenetic protein 2 (BMP-2) and basic fibroblast growth factor-2 (FGF-2) were loaded separately as dual growth factors, allowing for progressive drug release following the natural process of bone regeneration. The first burst release of FGF-2 triggered the proliferation of surrounding cells, and the subsequent release of BMP-2 stimulated their differentiation. The microstructure, surface potential, hardness, reduced Young's modulus, and wettability were assessed using scanning electron microscopy, nanoindentation, and water contact angle. The formation of apatite layers after immersion in simulated body fluid confirmed the bioactivity of this PEM. PEMs loaded with BMP-2 and FGF-2 showed a long sustained release of growth factors for up to 48 days. The biological properties were studied in vitro with rat bone mesenchymal stem cells (rBMSCs) and in vivo using a rat critical-sized calvarial defect model. PEMs loaded with growth factors further stimulated the proliferation and osteogenic differentiation of rBMSCs and the histology results indicated that new bone tissues could directly grow onto the PEMs. These findings suggest that PEM composite coating possesses significant potential for surface modification and long-term drug release of metallic implants to assist with bone restoration.

New Drugs on the Horizon for Functional and Motility Gastrointestinal Disorders

New Drugs on the Horizon for Functional and Motility Gastrointestinal Disorders

Spatially-directed angiogenesis using ultrasound-controlled release of basic fibroblast growth factor from acoustically-responsive scaffolds

Vascularization is a critical step following implantation of an engineered tissue construct in order to maintain its viability. The ability to spatially pattern or direct vascularization could be therapeutically beneficial for anastomosis and vessel in-growth. However, acellular and cell-based strategies to stimulate vascularization typically do not afford this control. We have developed an ultrasound-based method of spatially- controlling regenerative processes using acellular, composite hydrogels termed acoustically-responsive scaffolds (ARSs). An ARS consists of a fibrin matrix doped with a phase-shift double emulsion (PSDE). A therapeutic payload, which is initially contained within the PSDE, is released by an ultrasound-mediated process called acoustic droplet vaporization (ADV). During ADV, the perfluorocarbon (PFC) phase within the PSDE is vaporized into a gas bubble. In this study, we generated ex situ four different spatial patterns of ADV within ARSs containing basic fibroblast growth factor (bFGF), which were subcutaneously implanted in mice. The PFC species within the PSDE significantly affected the morphology of the ARS, based on the stability of the gas bubble generated by ADV, which impacted host cell migration. Irrespective of PFC, significantly greater cell proliferation (i.e., up to 2.9-fold) and angiogenesis (i.e., up to 3.7-fold) were observed adjacent to +ADV regions of the ARSs compared to -ADV regions. The morphology of the PSDE, macrophage infiltration, and perfusion in the implant region were also quantified. These results demonstrate that spatially-defined patterns of ADV within an ARS can elicit spatially-defined patterns of angiogenesis. Overall, these finding can be applied to improve strategies for spatially-controlling vascularization. Statement of significanceVascularization is a critical step following implantation of an engineered tissue. The ability to spatially pattern or direct vascularization could be therapeutically beneficial for inosculation and vessel in-growth. However, acellular and cell-based strategies to stimulate vascularization typically do not afford this control. We have developed an ultrasound-based method of spatially-controlling angiogenesis using acellular, composite hydrogels termed acoustically-responsive scaffolds (ARSs). An ARS consists of a fibrin matrix doped with a phase-shift double emulsion (PSDE). An ultrasound-mediated process called acoustic droplet vaporization (ADV) was used to release basic fibroblast growth factor (bFGF), which was initially contained within the PSDE. We demonstrate that spatially-defined patterns of ADV within an ARS can elicit spatially-defined patterns of angiogenesis in vivo. Overall, these finding can improve strategies for spatially-controlling vascularization.

Growth factor functionalized biodegradable nanocellulose scaffolds for potential wound healing application

Nanocellulose has been highlighted as one of the most promising biomaterials for biomedical applications with the potential to outperform conventional polymeric materials. However, the design of nanocellulose-based biomaterials for wound healing still requires precise control over biophysical and biochemical cues to direct a series of cellular activities in healing processes. The bioactive cellulose nanofibrils scaffolds with controlled release of basic fibroblast growth factors (bFGFs) were constructed for potential wound healing applications. The Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) analysis revealed the polyion complex interaction between the positively charged bFGFs with the negatively charged cellulose nanofibrils, which mimics the interaction between bFGFs and heparin sulfate in extracellular matrix in the body. Such association enables not only the storage of bFGFs in a readily available form and from where it is slowly released, but also potential protection of it from denaturation. The release profile of bFGFs from the CNF scaffolds was tailored by tuning the CNF surface chemistry and in situ deconstruction of the scaffolds. The in situ enzymatic deconstruction of the scaffolds provides a possibility to tune the bioavailability of bFGFs for cell growth and proliferation, and more importantly, to balance the scaffolds degradation and new tissue formation in wound healing. The MTT assay of cells proliferation and fluorescence imaging of cells cultured in the 3D scaffolds showed that the CNF scaffolds loaded with bFGF can significantly facilitate the proliferation of the cells, even if only a small amount of bFGF was loaded. Enzymatic deconstruction of the CNFs network further increases the bFGFs bioavailability, and promotes cell proliferation. This work may serve as an important step toward the development of nanocellulose-based biomaterials with tailored biophysical and biochemical cues for wound healing and other biomedical applications.

Adipose-Derived Stromal Cell-Sheets Sandwiched, Book-Shaped Acellular Dermal Matrix Capable of Sustained Release of Basic Fibroblast Growth Factor Promote Diabetic Wound Healing.

The management of diabetic wounds is a therapeutic challenge in clinical settings. Current tissue engineering strategies for diabetic wound healing are insufficient, owing to the lack of an appropriate scaffold that can load a large number of stem cells and induce the interaction of stem cells to form granulation tissue. Herein we fabricated a book-shaped decellularized dermal matrix (BDDM), which shows a high resemblance to native dermal tissue in terms of its histology, microstructure, and ingredients, is non-cytotoxic and low-immunogenic, and allows adipose-derived stromal cell (ASC) attachment and proliferation. Then, a collagen-binding domain (CBD) capable of binding collagen was fused into basic fibroblast growth factor (bFGF) to synthetize a recombinant growth factor (termed as CBD–bFGF). After that, CBD–bFGF was tethered onto the collagen fibers of BDDM to improve its endothelial inducibility. Finally, a functional scaffold (CBD–bFGF/BDDM) was fabricated. In vitro and in vivo experiments demonstrated that CBD–bFGF/BDDM can release tethered bFGF with a sustained release profile, steadily inducing the interaction of stem cells down to endothelial differentiation. ASCs were cultured to form a cell sheet and then sandwiched by CBD–bFGF/BDDM, thus enlarging the number of stem cells loaded into the scaffold. Using a rat model, the ASC sheets sandwiched with CBD–bFGF/BDDM (ASCs/CBD–bFGF/BDDM) were capable of enhancing the formation of granulation tissue, promoting angiogenesis, and facilitating collagen deposition and remodeling. Therefore, the findings of this study demonstrate that ASCs/CBD–bFGF/BDDM could be applicable for diabetic wound healing.

Complement-mediated release of fibroblast growth factor 2 from human RPE cells

PurposeComplement activation is associated with choroidal neovascularization (CNV) in age-related macular degeneration (AMD). Fibroblast growth factor 2 (FGF2) and membrane attack complex (MAC) are present in eyes of patients with CNV. Herein, we investigated the effect of complement activation on FGF2 release in human retinal pigment epithelial (RPE) cells. MethodsCultured human RPE cells were primed with an anti-RPE antibody and then treated with C1q-depleted human serum in the presence or absence of Tec kinases inhibitor (LFM-A13). 38 cytokines/chemokines levels were measured by Luminex technology. Secretion of FGF2 and interleukin (IL)-6 was assessed by ELISA. Tec protein was measured by Western blot. mRNA expression of FGF2, chemokine (C-X-C motif) ligand 1 (CXCL-1), and family members of Tec kinases was evaluated by qPCR. Cell viability and MAC deposition were determined by WST-1 assay and flow cytometry, respectively. ResultsComplement activation caused increased FGF2 and IL-6 release. FGF2 was released when C6-depleted human serum was reconstituted with C6. Anti-C5 antibody significantly attenuated complement-mediated FGF2 release, but not IL-6. FGF2 mRNA levels were not affected, while CXCL-1 mRNA levels were increased by complement activation. FGF2-containing extracellular vesicles were detected in response to complement challenge. Tec mRNA and protein were expressed in RPE cells. In the presence of LFM-A13, secretion of FGF2, but not IL-6, and MAC deposition were significantly decreased and cell viability was significantly increased in complement-treated cells when compared to controls. ConclusionsComplement plays an important role to release FGF2 from RPE cells. Tec kinase is involved in MAC formation and complement-mediated FGF2 release. This information suggests a role for complement activation to mediate neovascularization in conditions such as AMD, and may elucidate potential therapeutic targets.

Abstract 14842: Brain Fibroblast Growth Factor Receptor 4 Stimulation is Involved in High Phosphate Diet-Induced Skeletal Muscle Reflex Overactivation in Rats

An increasing number of studies have reported a deleterious role of inorganic phosphate (Pi) in promoting hypertension. Previously, we have shown high Pi diet-induced excessive pressor and sympathetic responses to muscle contraction in otherwise normal rats, which were primarily mediated by an overactive exercise pressor reflex (EPR), a reflex arising from contracting muscle. However, the mechanism underlying these abnormalities generated by excess Pi intake remains unclear. Dietary Pi is known to increase release of bone-derived fibroblast growth factor (FGF) 23 to regulate Pi homeostasis. Evidence suggests that FGF23 and FGF receptors (FGFRs) are also present in the central nervous system. The aim of this study was to determine the role of brain FGFRs in mediating augmented EPR activity induced by dietary Pi excess. Accordingly, we assessed cerebrospinal fluid FGF23 levels in Sprague-Dawley rats fed either a normal 0.6% Pi diet (NP) or a high 1.2% Pi diet (HP) for 12 weeks. To determine the role of central FGFRs in mediating the EPR, we measured mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) responses to hindlimb muscle contraction before and after intracerebroventricular (ICV) administration of either a selective FGFR4 inhibitor BLU9931 or a FGFR1/2/3 inhibitor AZD4547 in decerebrate NP and HP animals. Cerebrospinal fluid FGF23 levels were significantly higher in HP rats compared to NP rats (8.3±0.9 vs. 7.2±0.8 pM, P&lt;0.01). ICV BLU9931 injection markedly attenuated (all P&lt;0.01) the heightened MAP (Δ=41±14 vs. 20±14 mmHg) and RSNA (Δ=112±70 vs. 65±46 %) responses to EPR activation in HP animals, but did not significantly affect the responses in NP animals (ΔMAP=11±3 vs. 7±4 mmHg, ΔRSNA=21±17 vs. 15±5 %). MAP and RSNA responses to EPR stimulation were unchanged by ICV AZD4547 administration in NP or HP rats. In conclusion, our data demonstrate a novel action of central FGFR4 inhibition by reducing the high Pi diet-mediated skeletal muscle reflex overactivation. Importantly, the results implicate that activation of brain FGFR4 may lead to sympathetic dysregulation contributing to the abnormal hypertensive responsiveness after excess Pi consumption.

Adipocyte Piezo1 mediates obesogenic adipogenesis through the FGF1/FGFR1 signaling pathway in mice

White adipose tissue (WAT) expansion in obesity occurs through enlargement of preexisting adipocytes (hypertrophy) and through formation of new adipocytes (adipogenesis). Adipogenesis results in WAT hyperplasia, smaller adipocytes and a metabolically more favourable form of obesity. How obesogenic WAT hyperplasia is induced remains, however, poorly understood. Here, we show that the mechanosensitive cationic channel Piezo1 mediates diet-induced adipogenesis. Mice lacking Piezo1 in mature adipocytes demonstrated defective differentiation of preadipocyte into mature adipocytes when fed a high fat diet (HFD) resulting in larger adipocytes, increased WAT inflammation and reduced insulin sensitivity. Opening of Piezo1 in mature adipocytes causes the release of the adipogenic fibroblast growth factor 1 (FGF1), which induces adipocyte precursor differentiation through activation of the FGF-receptor-1. These data identify a central feed-back mechanism by which mature adipocytes control adipogenesis during the development of obesity and suggest Piezo1-mediated adipocyte mechano-signalling as a mechanism to modulate obesity and its metabolic consequences.

Controlled release of basic fibroblast growth factor from a peptide biomaterial for bone regeneration.

Self-assembled peptide scaffolds based on D-RADA16 are an important matrix for controlled drug release and three-dimensional cell culture. In this work, D-RADA16 peptide hydrogels were coated on artificial bone composed of nano-hydroxyapatite/polyamide 66 (nHA/PA66) to obtain a porous drug-releasing structure for treating bone defects. The developed materials were characterized via transmission electron microscopy and scanning electron microscopy. The proliferation and adhesion of bone mesenchymal stem cells (BMSCs) were examined by confocal laser microscopy and CCK-8 experiments. The osteogenic ability of the porous materials towards bone BMSCs was examined in vitro by staining with Alizarin Red S and alkaline phosphatase, and bioactivity was evaluated in vivo. The results revealed that nHA/PA66/D-RADA16/bFGF reduces the degradation rate of D-RADA16 hydrogels and prolongs sustained release of bFGF, which would promote BMSCs proliferation, adhesion and osteogenesis in vitro and bone repair in vivo. Thus, it deserves more attention and is worthy of further research.

Assessment of the low-speed centrifugation concept modified in the release of fibroblast growth factor-2 in Saudi healthy patient

Introduction: Alteration of the centrifugation time and protocol may impact the release of platelet-rich fibrin (PRF) scaffolds. The current study purpose was to investigate the released levels of fibroblast growth factor-2 (FGF-2) in standard PRF (S-PRF) and low-speed centrifugation concept known as advanced PRF (A-PRF and A-PRF+). Measurements were done at five times interval over 42 days. The aim was to assess the FGF release and the relation between initial platelet counts and the concentrations of FGF-2 release using the following technique: (1) S-PRF, (2) A-PRF, and (3) A-PRF+.Materials and Methods: Twenty-four blood samples were taken from eight random Saudi Arabian national healthy subjects enrolled in the investigation. Blood samples were processed using S-PRF, A-PRF, and A-PRF+ centrifugation protocols. Protein quantification was performed using enzyme-linked immunosorbent assay at 1, 7, 14, 28, and 42-day intervals.Results and Discussion: A statistically significant difference in the mean of FGF-2 measurement between protocols at the 7th day where both S-PRF and A-PRF were significantly higher than A-PRF+ (P < 0.012). Initial platelets' significant count for S-PRF, A-PRF, and A-PRF+ was on day 1, day 7, and 7th day, respectively. Both protocols S-PRF and A-PRF yielded significantly higher release of the FGF-2 when compared to A-PRF+ in Saudi healthy subjects.

Role of Bile Acids and Gut Microbiota in Parenteral Nutrition Associated Injury.

Total Parenteral Nutrition (TPN) is a life-saving therapy where all nutritional requirements are provided intravenously. While this therapy is essential for individuals unable to process their nutritional needs enterically, significant complications arise such as intestinal failure associated liver injury (IFALD). IFALD includes hepatic steatosis, cholestasis, inflammation, ultimately progressing to cirrhosis and portal hypertension and some patients may need liver transplantation. The exact mechanism underlying this condition is not well understood, but studies have recently suggested that changes in gut microbiota and intraluminal bile acid signaling are known to play a role in the development of IFALD. In enterohepatic circulation with normal enteral nutrition, gut Farnesoid X Receptor (FXR) is activated by bile acids, which triggers the release of Fibroblast Growth Factor 19 (FGF19) into portal circulation. FGF19 serves to regulate intrahepatic bile acid synthesis with enteric nutrition. This signaling pathway is impaired in TPN as studies indicate decreased serum levels of FGF19 in subjects receiving TPN. Finally, gut microbiota is severely altered in TPN due to intestinal hypomobility. The shift in gut microbiota affects our immune response and promotes endotoxins that negatively affect liver function. Targeting the pathways affecting gut microbiota and bile acid signaling has promise in treating TPN associated injuries.

Controlled release of basic fibroblast growth factor from a water-floatable polyethylene nonwoven fabric sheet for maintenance culture of iPSCs.

Basic fibroblast growth factor (bFGF) is an essential supplement for culture media to support the proliferation of human pluripotent stem cells, while preserving their pluripotency. However, it is extremely unstable under cell culture conditions at 37 °C. Therefore, a culture medium supplemented with bFGF needs to be changed every day to maintain an effective concentration of bFGF. This study aimed to create a bFGF-releasing material via simple bFGF adsorption following oxygen plasma treatment by using a water-floatable polyethylene (PE) nonwoven fabric sheet as a bFGF-adsorbent material. Preliminary oxygen plasma treatment enhanced bFGF adsorption onto the sheet by increasing its surface water wettability. Based on the bFGF concentration in the adsorption solution, the resulting bFGF-adsorbed sheet showed different bFGF-release profiles in the culture medium. The bFGF-adsorbed sheet prepared under optimum conditions released bFGF in a sustained manner, maintaining the bFGF concentration in the culture medium of human induced pluripotent stem cells (iPSCs) at ≥10 ng mL−1 even without medium change for as long as 3 d. The bFGF released from the sheet retained its biological activity to support colony formation of iPSCs while preserving their pluripotency. This type of bFGF-releasing sheet can be used as a new form of bFGF supplement for the culture media of stem cells and would make a significant contribution to stem cell-based research and development.

Evaluation of dual release of stromal cell-derived factor-1 and basic fibroblast growth factor with nerve conduit for peripheral nerve regeneration: An experimental study in mice.

The development of drug delivery systems has enabled the release of multiple bioactive molecules. The efficacy of nerve conduits coated with dual controlled release of stromal cell-derived factor-1 (SDF-1) and basic fibroblast growth factor (bFGF) for peripheral nerve regeneration was investigated. Sixty-two C57BL6 mice were used for peripheral nerve regeneration with a nerve conduit (inner diameter, 1 mm, and length, 7 mm) and an autograft. The mice were randomized into five groups based on the different repairs of nerve defects. In the group of repair with conduits alone (n = 9), a 5-mm sciatic nerve defect was repaired by the nerve conduit. In the group of repair with conduits coated with bFGF (n = 10), SDF-1 (n = 10), and SDF-1/bFGF (n = 10), it was repaired by the nerve conduit with bFGF gelatin, SDF-1 gelatin, and SDF-1/bFGF gelatin, respectively. In the group of repair with autografts (n = 10), it was repaired by the resected nerve itself. The functional recovery, nerve regeneration, angiogenesis, and TGF-β1 gene expression were assessed. In the conduits coated with SDF-1/bFGF group, the mean sciatic functional index value (-88.68 ± 10.64, p = .034) and the axon number (218.8 ± 111.1, p = .049) were significantly higher than the conduit alone group, followed by the autograft group; in addition, numerous CD34-positive cells and micro vessels were observed. TGF-β1 gene expression relative values in the conduits with SDF-1/bFGF group at 3 days (7.99 ± 5.14, p = .049) significantly increased more than the conduits alone group. Nerve conduits coated with dual controlled release of SDF-1 and bFGF promoted peripheral nerve regeneration.

Effect of autogenous growth factors released from platelet concentrates on the osteogenic differentiation of periodontal ligament fibroblasts: a comparative study.

BackgroundPlatelet concentrates have been used in tissue regeneration. The purpose of this study was to examine effects of growth factors released from leukocyte- and platelet-rich fibrin (L-PRF) and concentrated growth factor (CGF) on the osteogenic differentiation of periodontal ligament fibroblasts (PDLFs).MethodsLeukocyte- and platelet-rich fibrins, CGFs and PDLFs were obtained from New Zealand rabbits. The release of basic fibroblast growth factor (bFGF), bone morphogenetic protein 2 (BMP-2) and transforming growth factor β1 (TGF-β1) from L-PRFs and CGFs was measured at 5 h and 1, 3, 5, 7 days, using the enzyme linked immunosorbent assay. The PDLFs were treated with exudates of L-PRF or CGF. After the treatment, cell counting kit-8 assay was performed at day 1, 3, 5 and 7. Alkaline phosphatase (ALP) assay and Western blotting were applied at day 7. Three blocking antibodies were used to neutralize the proteins of bFGF, BMP-2 and TGF-β1.ResultsLeukocyte- and platelet-rich fibrin and CGF showed different growth factor release pattern, but similar accumulated concentration of these growth factors. PDLFs proliferation was significantly promoted by both L-PRF and CGF at day 1, 3 and 7, and CGF group was superior to L-PRF group at day 1 and 3. Both L-PRF and CGF significantly enhanced PDLFs ALP activity and protein expression of osteogenic markers. The osteopontin level was higher in CGF group than in L-PRF group, but no significant differences were found between two groups for ALP activity. Three blocking antibodies significantly downregulated both L-PRF and CGF induced osteogenic markers expression.ConclusionBoth CGF and L-PRF can promote the proliferation and osteogenic differentiation of PDLFs. The bFGF, BMP-2 and TGF-β1 are involved in both L-PRF and CGF induced osteogenic differentiation of PDLFs.

Chitin degradation enzyme-responsive system for controlled release of fibroblast growth factor-2

Chitin is widely found in fungal cell walls and arthropod exoskeletons, and is used as a biomedical material. However, chitin is not water-soluble, restricting its use for controlled release materials. We found that water-soluble chitosan can be acetylated to produce a chitin equivalent, or chitin gel. Chitin gel, produced by mixing chitosan solution with acetic anhydride, can be degraded by lysozyme and fetal bovine serum, so could provide an ideal means for controlled release in biological systems. We tested a combination of chitin gel with a chitin binding domain (CBD) fusion protein as a controlled release system regulated by chitin degradation. A fusion protein consisting of fibroblast growth factor 2 (FGF-2) fused to CBD bound the chitin gel, and was released time-dependently rather than as an initial burst during lysozyme degradation, suggesting that this system could provide a means for controlled drug release in biological systems. Contrastingly, the trinitrophenyl residue (TNP-X) covalently bound to chitin gel, and was released by lysozyme degradation with an initial burst. If release of CBD-FGF-2 were simply dependent on lysozyme degradation of the chitin gel, the release behavior of CBD-FGF-2 would be similar to that of TNP-X, with an initial burst. Therefore, we propose that CBD-FGF-2 repeats the cycle of binding, release, and re-binding to the chitin gel during degradation. This system allows for a time-dependent, controlled release of CBD-FGF-2 without an initial burst.

Controlled delivery of basic fibroblast growth factor (bFGF) using acoustic droplet vaporization stimulates endothelial network formation

The challenge of translating pro-angiogenic growth factors for therapeutic purposes has stimulated a myriad of biomaterials-based, delivery approaches. Many techniques rely on incorporating a growth factor into a hydrogel. The kinetics of release can be tuned based on the physiochemical properties of the growth factor and scaffold. We have developed an acoustically-responsive scaffold (ARS), whereby release of a growth factor is non-invasively and spatiotemporally controlled in an on-demand manner using focused ultrasound. An ARS consists of a fibrin matrix doped with a growth factor-loaded, sonosensitive emulsion. In this study, we used an ARS to investigate the impact of basic fibroblast growth factor (bFGF) release on endothelial tubule formation. The co-culture model of angiogenic sprouting consisted of endothelial cell-coated microbeads and dispersed fibroblasts. bFGF release correlated with the acoustic pressure applied while sprout length correlated with both the volume of bFGF-loaded emulsion in the ARS and acoustic pressure. Minimal bFGF release and sprouting were observed in the absence of ultrasound exposure. Staggering the release of bFGF via multiple ultrasound exposures did not affect sprouting. Additionally, sprouting did not display a dependence on the distance between each microbead and the ARS. Overall, these results highlight the potential of using ultrasound to control regenerative processes via the controlled delivery of a growth factor. Statement of SignificanceDue to the ineffectiveness of conventional routes of administration, implantable hydrogels are often used as matrices to deliver growth factors (GFs). Spatial control of release is typically realized using anisotropic constructs while temporal control is obtained by modifying matrix properties and GF-scaffold interactions. In this study, we demonstrate how focused ultrasound can be used to non-invasively and spatiotemporally control release of basic fibroblast growth factor (bFGF), in an on-demand manner, from a composite hydrogel. The acoustically-responsive scaffold (ARS) consists of a bFGF-loaded, monodispersed double emulsion embedded within a fibrin matrix. We demonstrate how controlled release of bFGF can stimulate endothelial network formation. These results may be of interest to groups working on controlled release strategies for GFs, especially in the context of stimulating angiogenesis.