Local Application Of Growth Factors Research Articles

Effect of natural-based biological hydrogels combined with growth factors on skin wound healing

Abstract Skin wound healing is a continuous and complex process affected by many factors. Growth factors play an important role in the process of wound healing. Local application of growth factors can significantly promote wound healing. However, the degradation and time dependence of growth factors require appropriate delivery systems to help them play a role in wound healing. In recent years, wound dressing products with hydrogels as matrix materials or main components have shown obvious advantages in promoting wound healing. By modifying the hydrogel or combining it with other factors or materials that are beneficial to wound healing, the healing effect can be further enhanced. This review will introduce the research status of growth factors and hydrogels based on natural biological materials in skin wound repair and review the effects and research progress of the combination of growth factors and hydrogels in skin wound healing.

Enhanced tissue regeneration through immunomodulation of angiogenesis and osteogenesis with a multifaceted nanohybrid modified bioactive scaffold.

Major traumatic tissue defects are common clinical problems often complicated by infection and local vascular dysfunction, processes which hinder the healing process. Although local application of growth factors or stem cells through various tissue engineering techniques are promising methods for the repair of tissue defects, limitations in their clinical application exist. Herein, we synthesized multifaceted nanohybrids composed of Quaternized chitosan (QCS), Graphene oxide (GO), and Polydopamine (PDA; QCS-GO-PDA). Covalent grafting of QCS and GO at a mass ratio of 5:1 (5QCS-1GO) displayed excellent biocompatibility and enhanced osteogenic ability, while addition of PDA (5QCS-1GO-PDA) reduced the level of reactive oxygen species (ROS). 5QCS-1GO-PDA was able to achieve wound tissue regeneration by reducing the inflammatory response and enhancing angiogenesis. Furthermore, Polylactic acid/hydroxyapatite (PLA/HA) composite scaffolds were printed using Selective Laser Sintering (SLS) and the hybrid nanomaterial (5QCS-1GO-PDA) was used to coat the PLA/HA scaffold (5QCS-1GO-PDA@PLA/HA) to be used for rapid bone regeneration. 5QCS-1GO-PDA not only improved angiogenesis and osteogenic differentiation, but also induced M2-type polarization of macrophages and promoted bone regeneration via the BMP2/BMPRs/Smads/Runx2 signaling pathway. The bidirectional enhanced healing ability of the multifaceted nanohybrids 5QCS-1GO-PDA provides a promising method of effectively treating tissue defects.

Tissue particularities and problems related to bone healing and fracture repair

Tissue particularities and problems related to bone healing and fracture repair

Flow-Induced Axial Vascularization: The Arteriovenous Loop in Angiogenesis and Tissue Engineering.

Fabrication of a viable vascular network providing oxygen supply is identified as one crucial limiting factor to generate more complex three-dimensional constructs. The arteriovenous loop model provides initial blood supply and has a high angioinductive potency, making it suitable for vascularization of larger, tissue-engineered constructs. Also because of its angiogenic capabilities the arteriovenous loop is recently also used as a model to evaluate angiogenesis in vivo. This review summarizes the history of the arteriovenous loop model in research and its technical and surgical aspects. Through modifications of the isolation chamber and its containing matrices, tissue generation can be enhanced. In addition, matrices can be used as release systems for local application of growth factors, such as vascular endothelial growth factor and basic fibroblast growth factor, to affect vascular network formation. A special focus in this review is set on the assessment of angiogenesis in the arteriovenous loop model. This model provides good conditions for assessment of angiogenesis with the initial cell-free environment of the isolation chamber, which is vascularized by the arteriovenous loop. Because of the angiogenic capabilities of the arteriovenous loop model, different attempts were performed to create functional tissue in the isolation chamber for potential clinical application. Arteriovenous loops in combination with autologous bone marrow aspirate were already used to reconstruct large bone defects in humans.

Strategies for stimulation of new bone formation: a critical review

Large bone defects, congenital or caused by diseases, trauma or surgery, do not heal spontaneously and are usually a clinical challenge in the orthopedic and dental practices. A critical review concerning strategies to substitute lost bone or stimulate osteogenesis was undertaken. Pivotal concepts ranging from traditional bone grafting and use of biomaterials to local application of growth factors and gene therapy were addressed, including critical comments on the efficacy and safety, difficulties, advantages and disadvantages of each method. The most predictable results are still obtained with autogenous bone graft, despite the inconveniences of morbidity and limited availability of graft material. Satisfactory results have been reported for recombinant bone morphogenetic proteins (rhBMPs)-2 and -7, which distinguish for their osteoinductive property, the difficulty being the need for a degradable carrier that allows its continuous release in a rate compatible to that of new bone formation. Other bone growth factors are currently under evaluation in preclinical models of bone defects; however their efficacy is also dependent on the competence of a delivery strategy and on an appropriate delineation of "which one", "which dose" and "when". Parameters of efficiency and safety for gene therapy are still being established. In conclusion, given the variety of growth factors involved in the complex cascade of bone repair and the biological interactions between them, it remains a challenge to accomplish the ideal strategy to stimulate reparational bone formation in specific conditions of the medical as in the dental practices.

Le BMP-7 nel trattamento delle necrosi dei condili femorali

Osteonecrosis of the femoral condyle is a well-recognized cause of spontaneous, acute, severe well-localised pain, usually at the antero-medial aspect of the knee joint. Treatment is conservative in the early stages. Surgical procedures include artroscopy, osteotomy, drilling of the lesion with or without bone grafting, allograft replacement and knee arthroplasty. Five patients diagnosed with osteonecrosis of the medial condyle were treated in our institute with core decompression and local application of growth factors (rhBMP-7). The patients were evaluated after 3, 6 and 12 months with objective evaluation, Knee Society Score and knee radiographs. Four knees were treated successfully, with no evidence of radiographic disease progression, and total knee replacement could be avoided. At 12 months’follow-up four patients report a satisfying outcome (Knee Society Score >80).

Construction and characterization of a thrombin-resistant designer FGF-based collagen binding domain angiogen

Humans demonstrate limited spontaneous endothelialization of prosthetic bypass grafts. However the local application of growth factors to prosthetic grafts or to injured blood vessels can provide an immediate effect on endothelialization. Novel chimeric proteins combining potent angiogens with extracellular matrix binding domains may localize to exposed matrices and provide sustained activity to promote endothelial regeneration after vascular interventions. We have ligated a thrombin-resistant mutant of fibroblast growth factor (FGF)-1 (R136K) with a collagen binding domain (CBD) in order to direct this growth factor to sites of exposed vascular collagen or selected bioengineered scaffolds. While FGF-1 and R136K are readily attracted to a variety of matrix proteins, R136K-CBD demonstrated selective and avid binding to collagen ∼4x that of FGF-1 or R136K alone ( P<0.05). The molecular stability of R136K-CBD was superior to FGF-1 and R136K. Its chemotactic activity was superior to R136K and FGF-1 (11±1% vs. 6±2% and 4±1%; P<0.01). Its angiogenic activity was similar to R136K and significantly greater than control by day 2 ( P<0.01). After day 3, FGF-1-treated endothelial cell's (EC) sprouts had regressed back to levels insignificant compared to the control group ( P=0.17), while both R136K and R136K-CBD continued to demonstrate greater sprout lengthening as compared to control ( P<0.0002). The mitogenic activity of all growth factors was greater than control groups (20% PBS); in all comparisons ( P<0.0001). This dual functioning angiogen provides proof of concept for the application of designer angiogens to matrix binding proteins to intelligently promote endothelial regeneration of selected matrices.

The effects of transforming growth factor β1, insulin-like growth factor 1 and leptin on the proliferation of fetal chondrocytes

One method to exogenously enhance the repair of articular cartilage is the local application of growth factors. This method is based on the chondrogenic effects of some agents and their potential ability to enhance cell migration. Human fetal chondrocytes were isolated and cultured. Their proliferation under the influence of different agents was microscopically evaluated. Fetal calf serum at 5% and 10% concentrations induced microscopically visible cell proliferation. Transforming growth factor beta one (5 and 10 ng/ml), insulin-like growth factor 1 (5 and 10 nmol/l) and leptin (1 and 2 ng/ml) accelerated proliferation of the cells towards the increasing gradient of the agents. Fibroblast growth factor beta (5 and 10 ng/ml), bone morphogenic protein two (10 ng/ml) and laminin (1 mg/ml) did not affect cell proliferation. This study suggests that different agents can play a role in the proliferation of fetal chondrocytes.

Treatment of Diabetic Foot Ulcers

The development of diabetic foot ulcers is a well-known complication of diabetes. The pathophysiological mechanism is complex, and different clinical presentations are possible, depending on the specific underlying pathology. Diabetic foot ulcers are usually caused by several factors acting in concert, with polyneuropathy, altered biomechanics, inadequate shoes and peripheral arterial disease (PAD) as major factors. Neuropathy is present in most patients with diabetic foot ulcers, while PAD is present in 30 - 50 %; infection can be diagnosed in up to 50% of patients presenting with a foot ulcer. Therefore careful examination of the patient and identification of these specific pathologies is needed before the start of any treatment. Because most patients have lost the natural protective mechanism to relieve pressure from the wound, off-loading of these ulcers is extremely important. For plantar foot ulcers total contact casting is the current standard: with this technique up to 90% of neuropathic ulcers can be healed within two months. The recognition and treatment of infection is equally important. Diagnosing infection is a challenge in these patients because signs and symptoms can be absent. The choice of the initial antimicrobial therapy is usually empiric and based on the severity of the infection, prior antibiotic use and local resistance to most common pathogens. Evaluation of the severity of PAD is indicated in many patients. Patients with critical limb ischemia should undergo revascularisation as soon as possible, and both endovascular treatment and bypass surgery are suitable interventions to improve tissue perfusion. Most other strategies to improve wound healing, such as local application of growth factors, have failed to show significant clinical benefits. Recently, negative pressure wound therapy was shown to improve wound healing in patients with a partial foot amputation in a large randomised trial. Many patients not only have foot problems but also other health problems such as cardiovascular and renal disease and self care problems. Therefore an integrated management programme is needed, in which optimal regulation of diabetes and associated co-morbidity, and regular communication and instruction of the patient and his or her caregivers are taken care of. Keywords: peripheral vascular disease (PAD), neuropathic foot ulcer, Neovascularisation, Peripheral Bypass Surgery, Hyperbaric Oxygen Therap

Local application of basic fibroblast growth factor increases the risk of local infection after trauma: An in-vitro and in-vivo study in rats

Introduction Local application of growth factors to stimulate wound and fracture healing is attracting increasing interest. We studied the effect of local application of a potent angiogenic growth factor, basic fibroblast growth factor (bFGF), on resistance to local infection after soft tissue trauma.Methods For in-vitro and in-vivo experiments, we used recombinant human bFGF. The in-vitro investigations were performed by isolation of human leukocyte fractions, cytokine analysis, phagocytosis assay, flow cytometry, and LDH assay. For the in-vivo investigation, a paired comparison of infection rates was carried out on Sprague-Dawley rats after standardized, closed soft tissue trauma and local, percutaneous bacterial inoculation of different concentrations of Staphylococcus aureus (2 × 104 to 2 × 107 colony-forming units (cfu)). The lower leg was treated with 1, 10 or 100 ng bFGF (16 animals for each concentration) and without bFGF (16 animals).Results Cytotoxic reactions due to the concentrations of bFGF used could be excluded in the in-vitro tests since incubations of isolated peripheral blood mononuclear cells (PBMCs) with increasing concentrations of bFGF for 24 h did not lead to an increase in the release of lactate dehydrogenase in the culture supernatants compared to corresponding control incubations without any bFGF added. A significant increase in cytokine release was observed after the co-incubation of PBMCs with 100 or 200 ng of the same bFGF that was used for the animal experiments. Furthermore, the capacity of phagocytes in whole blood to phagocytose bacteria was suppressed in the presence of 100 ng exogenously added bFGF. We found continuously reduced granulocytic phagocytosis in FGF-supplemented blood compared to non-supplemented blood.In the in-vivo investigation, the infection rate for the group without bFGF was 0.25. In the groups with 1, 10 and 100 ng bFGF, the infection rates were 0.5, 0.7 and 0.8, respectively. A dose-dependent increase in infection rate was observed after local application of bFGF, compared to the untreated control group. The difference in infection rates for the groups in which 10 and 100 ng bFGF was used, relative to the group without bFGF, was statistically significant.Interpretation If these initial results are confirmed for other potent angiogenic growth factors, then the local use of growth factors for stimulation of wound and bone healing—a main focus of current research in traumatology—will have to be reconsidered and preceded with a strict evaluation of the risks and benefits.

Prediction of biomechanical stability after callus distraction by high resolution scanning acoustic microscopy

Accurate clinical prediction of the resistance to fracture after callus distraction requires a detailed understanding of structural and elastic properties of the newly formed bone. We investigated 26 sheep that underwent middiaphyseal callus distraction at a rate of 0.5 mm every 12 h for 30 d using a standard unilateral fixator system. The sample population included four groups undergoing different treatments to improve bone healing, including bone grafting and the local application of growth factors. All animals were sacrificed eight weeks after the end of distraction. The fracture forces of the lengthened tibia and the contralateral control tibia from each animal were evaluated by biomechanical (four-point bending) testing. The microstructure and anisotropic acoustic impedance distributions were assessed by quantitative 50-MHz scanning acoustic microscopy. The relationships between resistance to fracture, structural properties and acoustic impedance of the newly formed callus tissue and adjacent cortical tissue were investigated. A significant linear multivariate regression model was developed that predicts the fracture force with a high accuracy (RMSE = 248 N, R 2 = 0.86, p < 0.0001). (E-mail: kay.raum@medizin.uni-halle.de)

The Osteogenic Potential of Stem Cell- and BMP2 Gene-Activating Bioceramic In Vivo

Stimulation of bone healing through local application of growth factors from implants may improve the clinical outcome in fracture treatments. However, the growth factors in reconstructive application require supraphysiologic dosing and considerable expense while hampering their clinical application. Genetic modification of mesenchymal stem cells (MSCs) to both produce and respond to osteogenic factors may have potential for use in enhancing bone healing. In this study, MSCs were genetically modified by a recombinant adenoviral containing the gene for human bone morphogenetic protein 2 (hBMP-2). The gene-transduced cells were incorporated with a porous beta-tricalcium phosphate (TCP) as a novel complex. We investigated osteogeneic potential of gene-transduced MSCs/ceramic and the ability of the complex on facilitating bone formation in a radius segmental defect of rabbits. In vitro results showed that there were apparent hBMP2 gene expression and protein synthesis in MSCs with hBMP2 stably transfection, whereas negative expression of hBMP2 in controls. Histological studies demonstrated that gene-transfected MSCs/ceramic composite appeared an ability of heterotopic osteogenesis. In the segmental bone defects, endochondrial ossification at fracture sites was found in both transfected and untransfected MSCs-ceramic composites. While the composite with hBMP2 transfection showed the earliest and the most effective healing of the segmental bone defects both radiographically and morphologically. Our results show that genetically modified MSCs/ceramics had enhanced osteogeneic capacity relative to unmodified MSCs or only ceramic implants. This study suggests that use of cell-and gene-activated bioceramics may offer promise for molecular design of implants to induce osteogenesis and enhance bone regeneration.

A new simplified technique for producing platelet-rich plasma: a short technical note.

A possible strategy to promote the wound-healing cascade in both soft and hard tissues is the preparation of an autologous platelet-rich plasma (PRP) to encourage the release of growth factors from activated platelets. In this process, PRP combines the advantage of an autologous fibrin clot that will aid in hemostasis as well as provide growth factors in high concentrations to the site of a tissue defect. The PRP preparation can be used as a biological enhancer in the healing of fractures and lumbar fusions. The local application of growth factors seems to promote initiation and early maturation of bone formation. Autologous bone or bone substitutes can be added to this mixture to increase the volume of grafting material. A simplified technique utilizing a commercially available separation system (GPS-Gravitational Platelet Separation System) is described. This system provides a less costly alternative to other previously described augmentation techniques and also presents a patient-friendly and operator-safe alternative. Further experimental studies of the actual concentrations of the growth factors in the PRP samples are necessary in order to validate the platelet concentration and growth-factor activation by laboratory evidence. In further prospective clinical trials, the safety and efficacy of PRP, in combination with autologous bone or bone graft substitutes, must be evaluated.

Influence of local application of basic fibroblast growth factor on resistance to local infection after standardized closed soft tissue trauma. An experimental study in rats

The aim of the study was to obtain information on the importance/influence of local application of an angiogenic potent growth factor (bFGF) on local infection resistance after soft tissue trauma.A paired comparison of infection rates was carried out on Sprague-Dawley rats after standardized, closed soft tissue trauma and local, percutaneous bacterial inoculation of different concentrations (2 x 10(4)-2 x 10(7)), whereby the lower leg was treated with 1, 10, and 100 ng bFGF (n=16 each) and without bFGF (n=16). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher's exact test ( p<0.05). For the group without bFGF application, the infection rate was 25%. In the groups with 1, 10, and 100 ng bFGF application, the infection rates were 50%, 69%, and 81%. The difference in the infection rates for the groups in which 10 and 100 ng bFGF were applied was highly significant ( p=0.032/ p=0.004) compared with the group without bFGF. If these initial results are confirmed for other angiogenic potent growth factors, then the local application of growth factors to stimulate wound and bone healing will need to be reconsidered and preceded by a very strict evaluation of the risks and benefits.

A novel controlled drug-delivery system for growth hormone applied to healing skin wounds in diabetic rats

Controlled release systems for drugs, hormones and growth factors can be particularly useful in tissue repair processes. These systems act as a biodegradable support containing the substance to be delivered, allowing their gradual release. In the past years, the local application of growth factors has acquired special relevance as a therapeutic option for use in subjects who show deficient tissue scarring, the hormone dose being the limiting factor for its success. In this study, the in vitro biocompatibility of a copolymer formed by vinylpyrrolidone and 2-hydroxyethyl methacrylate, used as an administration vehicle for hGH, was evaluated. The system was then tested in vivo in terms of its capacity for healing incisional wounds in healthy and diabetic rats. For the in vitro studies, polymer and hormone degradation rates were determined, and polymer biocompatibility was evaluated in fibroblast cultures. In the in vivo experiments, an incision was made in the back of the animals, and polymers discs with/without hGH, were introduced in the aperture. Morphological, immunohistochemical and morphometric evaluations were performed on wound tissue specimens 3-10 days after surgery. In vitro, the polymer was found to be biodegradable and showed no toxic effects on fibroblasts, the hormone being slowly released to the culture medium. In untreated diabetic rats, a delayed skin scarring and cell response were observed, compared to that noted in healthy animals. Skin closure, keratinisation and fibrosis occurred earlier in the presence of the polymer-hGH system. The use of this co-polymer as an administration vehicle for hGH improves the wound scarring process in the pathological setting of diabetes.

Improvement of fracture healing by systemic administration of growth hormone and local application of insulin-like growth factor-1 and transforming growth factor-β1

Fracture healing is influenced by numerous hormones, growth factors, and cytokines. The systemic administration of growth hormone (GH) has shown to accelerate bone regeneration. Local application of growth factors, such as insulin-like growth factor-1 (IGF-1) and transforming growth factor-β-1 (TGF-β1), are known to stimulate bone metabolism. Until now, the exact local and systemic mechanisms that lead to improved bone regeneration remain unclear. In addition, the effect of systemic administration of GH as compared with locally delivered growth factors on fracture healing in rats is not known. A midshaft fracture of the right tibia of 5-month-old female Sprague-Dawley rats (n = 80) was intramedullary stabilized with IGF-1 and TGF-β1 coated vs. uncoated titanium K-wires. The growth factors were incorporated in a poly(D,L-lactide) (PDLLA) coating and released continuously throughout the experiment. Recombinant species-specific (rat) GH was applied systemically (2 mg/kg body weight) by daily subcutaneous injection and compared with a placebo group. The healing process was radiologically monitored. Twenty-eight days after fracture biomechanical torsional testing was performed. The consolidation and callus composition, including quantification of cartilage and mineralized tissue, was traced in histomorphometrical investigations using an image analysis system. Both methods, the systemic administration of GH and the local application of growth factors, showed significant biomechanical and histological effects on fracture healing. The local growth factor application showed a stronger effect on fracture healing than the systemic GH injection. The combined application of both methods did not accelerate the effect on bone healing compared with the single application. It is therefore concluded that combining local and systemic stimulating methods does not provide further additive effects with regard to fracture healing.

Insulin-like growth factor-1 and transforming growth factor-β1 accelerates osteotomy healing using polylactide-coated implants as a delivery system: a biomechanical and histological study in minipigs

Stimulation of bone healing and bone formation through local application of growth factors from implants may improve the clinical outcome in fracture treatment. Previous studies demonstrated a high mechanical stability of a thin poly(d,l-lactide) (PDLLA) coating on metallic implants that can withstand the process of intramedullary insertion. Following an initial peak, 80% of incorporated insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1) were released continuously, within 42 days. The goal of the present study is evaluation of the coated implants on fracture healing in a large animal model. A midshaft osteotomy (1 mm gap) of the right tibia of Yucatan minipigs was stabilized with uncoated vs. coated titanium interlocking nails (5 mm). X-ray examinations and blood analyses (including IGF-1 and IGF-binding proteins) were performed, and body weight and body temperature were taken throughout the experiment. After 28 days, both tibiae were dissected for mechanical torsional testing and histomorphometric analyses. No differences were found in the blood analyses, body weight, or temperature due to the coating or the incorporated growth factors between the groups. X-ray examinations revealed a faster consolidation of the osteotomy in the growth factor-treated group. Biomechanical testing showed a significantly higher torsional stiffness and maximum load. Progressive remodeling was observed in the histological and histomorphometric analyses with a larger callus volume in the growth factor group compared with the control groups. We conclude that local application of growth factors from a biodegradable PDLLA coating of intramedullary implants accelerates bone healing in a large animal model without systemic side effects.

Local application of growth factors (insulin-like growth factor-1 and transforming growth factor-β1) from a biodegradable poly( d,l-lactide) coating of osteosynthetic implants accelerates fracture healing in rats

In vitro and in vivo studies have demonstrated an osteoinductive effect of growth factors such as insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1). However, for therapeutic use in fracture treatment, questions remain with regard to the local application of these proteins. A controlled, local release of growth factors from a biodegradable polylactide coating of osteosynthetic implants may have a stimulating effect on fracture healing. Such implants could stabilize the fracture and their bioactive surface could function simultaneously as a local drug-delivery system. Previous studies have demonstrated the high mechanical stability of an approximately 10–14-μm-thick poly( d,l-lactide) (PDLLA) coating on metallic implants, which can even withstand the process of intramedullary insertion. Following an initial peak, 80% of incorporated growth factors IGF-1 and TGF-β1 were continuously released within 42 days. The effect of locally applied IGF-1 and TGF-β1 from a biodegradable PDLLA coating of intramedullary implants on fracture healing was investigated in a rat model. Midshaft fractures of the right tibia of 5-month-old female Sprague-Dawley rats (n = 127) were stabilized with coated vs. uncoated titanium Kirschner wires. X-ray examinations and blood analyses were performed, and body weight and body temperature measurements were taken throughout the experimental period. After 28 and 42 days, respectively, tibiae were dissected for mechanical torsional testing and histomorphometrical analyses. X-rays demonstrated an almost completely consolidated fracture, biomechanical testing showed a significantly higher maximum load and torsional stiffness, and histological and histomorphometric analyses demonstrated progressed remodeling after 28 and 42 days in the group treated with growth factors as compared with controls. Interestingly, the PDLLA coating itself revealed a positive effect on fracture healing even without incorporated growth factors. No systemic changes of serum parameters, including IGF-1 and IGF binding proteins, and no differences in body weight and body temperature were observed within and between groups. These findings suggest that the local application of growth factors from a biodegradable PDLLA coating of osteosynthetic implants accelerates fracture healing significantly without systemic side effects.

Comparison of systemic and local application of growth factors on gastric secretion and ulcer healing

Comparison of systemic and local application of growth factors on gastric secretion and ulcer healing

Comparison of systemic and local application of growth factors on gastric secretion and ulcer healing

Comparison of systemic and local application of growth factors on gastric secretion and ulcer healing