Delivery Of Insulin-like Growth Factor-1 Research Articles

Insulin-Like Growth Factor Binding Protein-3 (IGFBP-3): Unraveling the Role in Mediating IGF-Independent Effects Within the Cell.

Insulin-like growth factor (IGF) binding protein-3 (IGFBP-3), one of the six members of the IGFBP family, is a key protein in the IGF pathway. IGFBP-3 can function in an IGF-dependent as well as in an IGF-independent manner. The IGF-dependent roles of IGFBP-3 include its endocrine role in the delivery of IGFs from the site of synthesis to the target cells that possess IGF receptors and the activation of associated downstream signaling. IGF-independent role of IGFBP-3 include its interactions with the proteins of the extracellular matrix and the proteins of the plasma membrane, its translocation through the plasma membrane into the cytoplasm and into the nucleus. The C-terminal domain of IGFBP-3 has the ability to undergo cell penetration therefore, generating a short 8-22-mer C-terminal domain peptides that can be conjugated to drugs or genes for effective intracellular delivery. This has opened doors for biotechnological applications of the molecule in molecular medicine. The aim of this this review is to summarize the complex roles of IGFBP-3 within the cell, including its mechanisms of cellular uptake and its translocation into the nucleus, various molecules with which it is capable of interacting, and its ability to regulate IGF-independent cell growth, survival and apoptosis. This would pave way into understanding the modus operandi of IGFBP-3 in regulating IGF-independent processes and its pleiotropic ability to bind with potential partners thus regulating several cellular functions implicated in metabolic diseases, including cancer.

Abstract TP96: Neuroprotective Effects of IGF-1 in Middle-Aged Females Can Be Replicated by Antagomirs to microRNA (miR)-92b and miR-33a

Background: Our previous studies show that intracerebroventricular (ICV) delivery of Insulin-like growth factor (IGF)-1 reduces MCAo-induced infarction in middle-aged female rats. Analysis of ischemic tissue at 4h showed that IGF1 treatment significantly reduced the expression of a group of miRNAs. To determine if inhibiting these miRNAs could replicate IGF-1-mediated neuroprotection, we examined the effects of antagomirs to miR-33a (A-mir33a) and miR-92b (A-mir92b) in in vivo and in vitro models of ischemia. Methods: Middle-aged (12 mo) acyclic female rats were subject to intraluminal MCAo for 90 min followed by reperfusion. Animals received a single tail vein injection of A-miR-33a, A-miR-92b, A-miR-33a+A-miR-92b or scrambled oligos (7ug/kg bwt) after 4h of reperfusion. We evaluated infarct volume (TTC staining) at 2d post stroke and behavioral recovery using neurological scores and adhesive removal test (ART). In parallel, human brain endothelial cell cultures were exposed to oxygen-glucose deprivation (OGD) in the presence of A-mir-33a, A-mir-92b or scrambled oligos. The integrity of the cell monolayer was assessed by tomato-lectin staining and cell death was assayed by LDH. Results: Single injection of A-mir92b during the acute stroke phase reduced infarct volume (p<0.04) and improved sensorimotor behavior (p<0.04) while A-mir33a treated animals were not different from scrambled control. However, the combination of A-mir-33a+A-mir-92b resulted in significantly smaller infarct volumes (p<0.04), less motor impairment (neurological score; p<0.02) and sensorimotor deficits (ART; p<0.05). In vitro studies showed that neither of the antagomirs reduced media LDH under OGD. As reported previously, OGD caused cell retraction and A-mir33a notably preserved the cell geometry (continuous lectin staining) to maintain the monolayer integrity and was similar to the normoxic control. Conclusions: IGF-1 regulated microRNAs appear to modulate specific aspects of stroke recovery. IV delivery of a combination of miRNA inhibitors may replicate the neuroprotective actions of IGF-1, thus providing a safer alternate to ICV delivery of IGF-1. Supported by R56 NS074895 and RF1 AG04218906

Insulin-like growth factor-1 inhibits spreading depression-induced trigeminal calcitonin gene related peptide, oxidative stress & neuronal activation in rat

Migraineurs can show brain hyperexcitability and oxidative stress that may promote headache. Since hyperexcitability can enhance oxidative stress which promotes hyperexcitability, ending this feed-back loop may reduce migraine. Neocortical spreading depression, an animal model of migraine begins with hyperexcitability and triggers oxidative stress in the neocortical area involved and in the trigeminal system, which is important to pain pathway nociceptive activation in migraine. Additionally, oxidative stress causes increased trigeminal ganglion calcitonin gene-related peptide release and oxidative stress can reduce spreading depression threshold. Insulin-like growth factor-1 significantly protects against spreading depression in vitro by reducing oxidative stress and it is effective against spreading depression after intranasal delivery to animals. Here, we used adult male rats and extend this work to study the trigeminal system where insulin-like growth factor-1 receptors are highly expressed. Recurrent neocortical spreading depression significantly increased surrogate markers of trigeminal activation - immunostaining for trigeminal ganglion oxidative stress, calcitonin gene related peptide levels and c-fos in the trigeminocervical complex versus sham. These effects were significantly reduced by intranasal delivery of insulin-like growth factor-1 a day before recurrent neocortical spreading depression. Furthermore, intranasal treatment with insulin-like growth factor-1 significantly reduced naïve levels of trigeminal ganglion calcitonin gene related peptide versus sham with no impact on blood glucose levels. Intranasal delivery of insulin-like growth factor-1 not only mitigates neocortical spreading depression, a cause of migraine hyperexcitability modeled in animals, but also when neocortical spreading depression is triggered by supra-threshold stimuli, insulin-like growth factor-1 effectively reduces nociceptive activation in the trigeminal system.

Combined delivery of VEGF and IGF-1 promotes functional innervation in mice and improves muscle transplantation in rabbits

Microvascular muscle transfer is the gold standard for reanimation following chronic facial nerve paralysis, however, despite the regenerative capacity of peripheral motor axons, poor reinnervation often results in sub-optimal function. We hypothesized that injection of alginate hydrogels releasing growth factors directly into donor tissue would promote reinnervation, muscle regeneration, and function. A murine model of sciatic nerve ligation and neurorrhaphy was first used to assess the ability of gel delivery of vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1) to promote functional reinnervation. VEGF + IGF-1 gel delivery to aged mice resulted in prolonged ability to control toe movement, increased toe spreading, and improved static sciatic index score, indicative of improved sciatic nerve and neuromuscular junction function. Further, a 26% increase in muscle fiber area, and 2.8 and 3.0-fold increases in muscle contraction force and velocity, respectively, were found compared to blank alginate in the murine model. This strategy was subsequently tested in a rabbit model of craniofacial gracilis muscle transplantation. Electromyography demonstrated a 71% increase in compound muscle action potential 9 weeks after transplantation following treatment with VEGF + IGF-1 alginate, compared to blank alginate in the rabbit model. Improving functional innervation in transplanted muscle via a hydrogel source of growth factors may enhance the therapeutic outcomes of facial palsy treatments and, more broadly, muscle transplantations.

Polymeric mesh and insulin-like growth factor 1 delivery enhance cell homing and graft-cartilage integration.

Cartilage injury, such as full-thickness lesions, predisposes patients to the premature development of osteoarthritis, a degenerative joint disease. While surgical management of cartilage lesions has improved, long-term clinical efficacy has stagnated, owing to the lack of hyaline cartilage regeneration and inadequate graft-host integration. This study tests the hypothesis that integration of cartilage grafts with native cartilage can be improved by enhancing the migration of chondrocytes across the graft-host interface via the release of chemotactic factor from a degradable polymeric mesh. To this end, a polylactide-co-glycolide/poly-ε-caprolactone mesh was designed to localize the delivery of insulin-like growth factor 1 (IGF-1), a well-established chondrocyte attractant. The release of IGF-1 (100ng/mg) enhanced cell migration from cartilage explants, and the mesh served as critical structural support for cell adhesion, growth, and production of a cartilaginous matrix in vitro, which resulted in increased integration strength compared with mesh-free repair. Further, this neocartilage matrix was structurally contiguous with native and grafted cartilage when tested in an osteochondral explant model in vivo. These results demonstrate that this combined approach of a cell homing factor and supportive matrix will promote cell-mediated integrative cartilage repair and improve clinical outcomes of cartilage grafts in the treatment of osteoarthritis.

Abstract 107: IGF-1 Nanoparticles Improve Functional Recovery After Nerve Repair

PURPOSE: Insulin-like growth factor 1 (IGF-1) is a potent mitogen with well-described trophic and anti-apoptotic effects on neurons, myocytes, and Schwann cells (SCs). Local delivery of IGF-1 is limited by its short half-life. The aims of this study are to (1) encapsulate IGF-1 into biodegradable nanoparticles (NPs) that stabilize IGF-1 in its bioactive state and enable sustained release at target tissue sites that persist throughout the regenerative period; and (2) assess the efficacy of locally delivered IGF-1 NPs in augmenting axonal regeneration while also reducing denervation-induced muscle atrophy and SC senescence to thereby improve functional recovery following nerve injury. METHODS: (1) NP Fabrication: IGF-1 was first complexed with dextran sulfate to create hydrophobic ionic paired (HIP) complexes, which were then encapsulated in biodegradable NPs. Varying ratios of HIP:polymer were evaluated to maximize loading efficiency and release kinetics. In vitro NP release kinetics were evaluated and mitogenic activity of released IGF-1 was compared to native IGF-1. (2) The effects of locally-delivered IGF-1 NPs on denervated muscle and Schwann cells were assessed in a rat median nerve transection-without-repair model. The effects of IGF-1 NPs on axonal regeneration, muscle atrophy and reinnervation, and recovery of forepaw function were assessed in a model in which chronic denervation is induced prior to nerve repair; functional recovery was assessed weekly with stimulated grip strength testing prior to sacrifice at 15 weeks for histologic analyses. RESULTS: (1) Fabrication of uniform NPs with an encapsulation efficiency of 83.2% was achieved. NPs composed of 1:5 PEG5k-PCL40k yielded optimal release of IGF-1. Near-zero-order release of IGF-1 can be achieved for at least 70 days and released IGF-1 exhibits comparable bioactivity to native IGF-1. (2) IGF-1 treated animals recovered significantly more forceful grip strength compared to negative controls. IGF-1 NP treatment limits muscle atrophy during periods of denervation compared to negative controls (620 vs. 340μm2, respectively; p <0.05). CONCLUSION: Encapsulation of bioactive IGF-1 with sustained release for over 70 days was achieved. IGF-1 NP treatment in vivo limits muscle atrophy during denervation and improves functional recovery of forelimb grip strength.

Graphene oxide-PLGA hybrid nanofibres for the local delivery of IGF-1 and BDNF in spinal cord repair

Spinal cord injury (SCI) can lead to permanent and severe functional impairment below the lesion level and is still one of the most challenging clinical problems. The treatment of SCI has progressed with the development of tissue engineering techniques. Insulin-like growth factor 1 (IGF-1) and brain-derived neurotrophic factor (BDNF) are growth factors closely related to nerve regeneration. In this study, IGF-1 and BDNF were successfully immobilized on biodegradable graphene oxide (GO)-incorporated PLGA (PLGA/GO) electrospun nanofibres. The effect of PLGA/GO nanofibres with immobilized IGF-1 and BDNF on neurogenesis was investigated in vitro and in vivo utilizing MTT assays, immunofluorescence, motor function detection and histology observations. We demonstrated that PLGA/GO nanofibres loaded with IGF-1 and BDNF not only protected NSCs from oxidative stress induced by H2O2 but also enhanced NSC proliferation and neuronal differentiation in vitro. The in vivo study of an SCI animal model demonstrated that local delivery of IGF-1 and BDNF immobilized to PLGA/GO nanofibres significantly improved functional locomotor recovery, reduced cavity formation and increased the number of neurons at the injury site. Our study indicated that PLGA/GO is an effective carrier for IGF-1 and BDNF delivery and that immobilization of IGF-1 and BDNF onto PLGA/GO nanofibres has a great potential as a nerve implant for spinal cord injury applications.

Insulin-Like Growth Factor-1–Loaded Polymeric Poly(Lactic-Co-Glycolic) Acid Microspheres Improved Erectile Function in a Rat Model of Bilateral Cavernous Nerve Injury

BackgroundPrevious studies have documented improvement in erectile function after bilateral cavernous nerve injury (BCNI) in rats with the use of pioglitazone. Our group determined this improvement to be mediated by the insulin-like growth factor-1 (IGF-1) pathway. AimTo eliminate the systemic effects of pioglitazone and evaluate the local delivery of IGF-1 by polymeric microspheres after BCNI in the rat. MethodsMale Sprague–Dawley rats aged 10–12 weeks were assigned at random to 3 groups: sham operation with phosphate buffered saline (PBS)-loaded microspheres (sham group), crush injury with PBS-loaded microspheres (crush group), and crush injury with IGF-1–loaded microspheres (IGF-1 group). Poly(lactic-co-glycolic) acid microspheres were injected underneath the major pelvic ganglion (MPG). IGF-1 was released at approximately 30 ng/mL/day per MPG per rat. OutcomesFunctional results were demonstrated by maximal intracavernosal pressure (ICP) normalized to mean arterial pressure (MAP). Protein-level analysis data of IGF-1 receptor (IGF-1R), extracellular signal–regulated kinase (ERK)-1/2, and neuronal nitric oxide synthase (nNOS) were obtained using Western blot analysis and immunohistochemistry for both the cavernosal tissue and the MPG and cavernous nerve (CN). ResultsAt 2 weeks after nerve injury, animals treated with IGF-1 demonstrated improved erectile functional recovery (ICP/MAP) at all voltages compared with BCNI (2.5V, P = .001; 5V, P < .001; 7.5V, P < .001). Western blot results revealed that up-regulation of the IGF-1R and ERK-1/2 in both the nervous and erectile tissue was associated with improved erectile function recovery. There were no significant between-group differences in nNOS protein levels in cavernosal tissue, but there was an up-regulation of nNOS in the MPG and CN. Immunohistochemistry confirmed these trends. Clinical TranslationLocal up-regulation of the IGF-1R in the neurovascular bed at the time of nerve injury may help men preserve erectile function after pelvic surgery, such as radical prostatectomy, eliminating the need for systemic therapy. Strengths & LimitationsThis study demonstrates that local drug delivery to the MPG and CN can affect the CN tissue downstream, but did not investigate the potential effects of up-regulation of the growth factor receptors on prostate cancer tissue. ConclusionStimulating the IGF-1R at the level of the CN has the potential to mitigate erectile dysfunction in men after radical prostatectomy, but further research is needed to evaluate the safety of this growth factor in the setting of prostate cancer.Haney NM, Talwar S, Akula PK, et al. Insulin-Like Growth Factor-1–Loaded Polymeric Poly(Lactic-Co-Glycolic) Acid Microspheres Improved Erectile Function in a Rat Model of Bilateral Cavernous Nerve Injury. J Sex Med 2019;16:383–393.

Enhancement of neural stem cell survival, proliferation and differentiation by IGF-1 delivery in graphene oxide-incorporated PLGA electrospun nanofibrous mats.

The mammalian central nervous system has a limited ability for self-repair under injury conditions. The treatment of nerve injuries has been revolutionised with the development of tissue engineering techniques. However, the lack of bioactivity has severely restricted the application of biodegradable implants for neurogenesis. Therefore, surface modification of biomaterials is crucial to improve their bioactivity and promote endogenous repair mechanisms for nerve regeneration. Insulin-like growth factor 1 (IGF-1) is a growth factor for neuroprotection and neurogenesis. In this study, IGF-1 was successfully immobilised on graphene oxide (GO)-incorporated poly(lactic-co-glycolic acid) (PLGA) biodegradable electrospun nanofibres. For the in vitro investigation, neural stem cells (NSCs) were cultured on different nanofibres to observe various cellular activities. GO enhanced NSC survival under H2O2 pre-treatment and neuronal differentiation to some extent. More importantly, the immobilisation of IGF-1 onto the PLGA/GO nanofibres resulted in significantly increased NSC survival, proliferation, and differentiation. Findings from this study revealed that using PLGA/GO electrospun nanofibres to immobilise IGF-1 has excellent potential for the enhancement of the neuroprotective and neurogenic effects of nerve implants.

Ultrasound-Targeted Microbubble Destruction Delivery ofInsulin-Like Growth Factor 1cDNA andTransforming Growth Factor BetaShort Hairpin RNA Enhances Tendon Regeneration and Inhibits Scar FormationIn Vivo

Ultrasound-targeted microbubble destruction (UTMD), which has been successfully used for the treatment of many diseases, offers a promising noninvasive approach for target-specific gene delivery. This study investigated the UTMD delivery of insulin-like growth factor 1 (IGF-1) cDNA and transforming growth factor beta (TGF-β) short hairpin RNA for Achilles tendon injury in rats. Briefly, 168 rats with an injured Achilles tendon were randomly divided into seven groups: (1) IGF-1 + UTMD, (2) TGF-β + UTMD, (3) IGF-1 + TGF-β + UTMD, (4) control, (5) IGF-1, (6) TGF-β, and (7) IGF-1 + TGF-β. At 2, 4, 8, and 12 weeks post treatment, six rats from each group were euthanized. IGF-1 expression and TGF-β expression were evaluated using an adhesion index score, pathological examination, quantitative real-time reverse transcription polymerase chain reaction, Western blotting, and biomechanical measurement. The lowest adhesion index score, the lightest inflammation, the highest 4,6-diamidino-2-phenylindole nuclear counter signals, the highest IGF-1 expression, and the lowest TGF-β expression were observed in group 3 (p < 0.05). Furthermore, higher expression of IGF-1 mRNA was observed in groups 1 and 3, while lower expression of TGF-β mRNA was observed in groups 2 and 3 (p < 0.05). The UTMD groups showed a higher transfection efficiency than the groups without UTMD. Downregulation of type III collagen and upregulation of type I collagen were observed in groups 1-3. Moreover, during weeks 4, 8, and 12, greater maximum load and tensile stress were observed in group 3 compared to the other groups (p < 0.05), while the highest tendon stiffness was observed in week 12 (p < 0.05). To conclude, the results suggest that UTMD delivery of IGF-1 and TGF-β offers a promising treatment approach for tendon injury in vivo.

PD21-10 AN EXPERIMENTAL STUDY OF TOPICAL INSULIN-LIKE GROWTH FACTOR-1 DELIVERY TO IMPROVE URETHRAL WOUND HEALING IN A RABBIT MODEL

You have accessJournal of UrologyTrauma/Reconstruction/Diversion: Urethral Reconstruction (including Stricture, Diverticulum) I1 Apr 2018PD21-10 AN EXPERIMENTAL STUDY OF TOPICAL INSULIN-LIKE GROWTH FACTOR-1 DELIVERY TO IMPROVE URETHRAL WOUND HEALING IN A RABBIT MODEL Masayuki Shinchi, Toshihiro Kushibiki, Yoshine Mayumi, Keiichi Ito, Tomohiko Asano, Miya Ishihara, and Akio Horiguchi Masayuki ShinchiMasayuki Shinchi More articles by this author , Toshihiro KushibikiToshihiro Kushibiki More articles by this author , Yoshine MayumiYoshine Mayumi More articles by this author , Keiichi ItoKeiichi Ito More articles by this author , Tomohiko AsanoTomohiko Asano More articles by this author , Miya IshiharaMiya Ishihara More articles by this author , and Akio HoriguchiAkio Horiguchi More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1165AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urethral stricture is characterized by a narrowing of the urethra with formation of scar tissue, and few anti-fibrotic agents have been used to prevent urethral stricture formation after urethral injury. Insulin-like growth factor-1 (IGF-1) has emerged as an anti-fibrotic agent and we evaluated the effect of topical IGF-1 delivery on urethral wound healing after urethral injury. METHODS We made urethral catheters coated either with IGF-1 impregnated collagen hydrogel or with only collagen hydrogel. A total of 31 male Japanese white rabbits (2.5 to 3.0 kg) were divided into 3 groups after their urethras were injured by electrocoaglation using spherical monopolar electrocautery. Group 1 (n = 5, control group) received no additional treatment after urethral injury. Group 2 (n = 6, collagen hydrogel group) had a urethral catheter coated with only collagen hydrogel inserted immediately after urethral injury. Group 3 (n = 10, IGF-group) had a urethral catheter coated with IGF-1 impregnated collagen hydrogel inserted immediately after urethral injury. Fourteen days after urethral injury, retrograde urethrography and urethroscopy (diameter 2.7 mm) were performed to evaluate the injured urethra, and the injured segments were also histologically evaluated. RESULTS The mean urethral diameter on urethrography in group 3 (5.6 mm) was the largest among the three groups (1.9 mm in group 1 and 4.1 mm in group 2, p < 0.01, figure upper panel). The ratio of urethral lumen in injured urethra to that in normal urethra in group 3 (56.0%) was the largest among the 3 groups (21.0 % in group 1 and 37.6 % in group 2, p < 0.01, figure lower panel). Nine of 10 (90.0%) had a urethral lumen large enough for passage of a urethroscope, which is higher than the fraction in the other groups (1 of 5, 20.0%, in group 1 and 4 of 6, 66.7%, in group 2). The mean injured area not covered with urethral epithelium in group 3 (9.45 mm2) was the smallest among the three groups (36.26 mm2 in group 1 and 26.24 mm2 in group 2, p < 0.05). CONCLUSIONS Topical IGF-1 delivery with collagen hydrogel significantly improved urethral wound healing and prevented urethral narrowing. Thus it might be useful in the prevention of urethral stricture after internal urethrotomy or urethral dilation. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e471 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Masayuki Shinchi More articles by this author Toshihiro Kushibiki More articles by this author Yoshine Mayumi More articles by this author Keiichi Ito More articles by this author Tomohiko Asano More articles by this author Miya Ishihara More articles by this author Akio Horiguchi More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Systemic administration of scAAV9-IGF1 extends survival in SOD1G93A ALS mice via inhibiting p38 MAPK and the JNK-mediated apoptosis pathway

Amyotrophic lateral sclerosis (ALS) is closely associated with a reduction of neurotrophic factors in the central nervous system (CNS). Insulin-like growth factor 1 (IGF1)-encoding vectors delivered via intramuscular and intraparenchymal spinal cord injections have conferred therapeutic benefits in ALS model mice, although the development of a noninvasive delivery route is still needed. Intravenous administration of adeno-associated virus (AAV) vectors has been used to induce expression of neurotrophic genes in the lumbar spinal cords of adult mice. Therefore, the aim of this study was to investigate the effect of intravenous delivery of human IGF1 by self-complementary adeno-associated virus (scAAV) vectors in 90-day-old SOD1-G93A ALS mice. We found that IGF1 treatment decreased motor neuron death, mitigated myelin pathology in the ventral root, and prolonged the lifespan in SOD1-G93A mice. We also discovered that IGF1 inhibited phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) and the c-Jun-N-terminal kinase (JNK) pathway in the lumbar spinal cord, as evidenced by downregulated phosphorylated p38 and phosphorylated JNK. Furthermore, we detected the levels of proteins involved in the apoptosis pathway and found that the apoptotic inhibitor Bcl2 increased and the apoptotic promoter Bax, caspase 3, and caspase 9 decreased. In addition, the pro-inflammatory factor TNF-α was reduced after IGF1 treatment. In conclusion, we report a convenient and noninvasive ALS treatment method. Our results revealed a previously unrecognized role of IGF1 in p38 MAPK and the JNK-mediated pathway and its potential role as a therapeutic target for ALS.

Enhancing engineered vascular networks in vitro and in vivo: The effects of IGF1 on vascular development and durability

Creation of functional, durable vasculature remains an important goal within the field of regenerative medicine. Engineered biological vasculature has the potential to restore or improve human tissue function. We hypothesized that the pleotropic effects of insulin-like growth factor 1 (IGF1) would enhance the engineering of capillary-like vasculature. The impact of IGF1 upon vasculogenesis was examined in in vitro cultures for a period of up to 40days and as subcutaneous implants within immunodeficient mice. Co-cultures of human umbilical vein endothelial cells and human bone marrow-derived mesenchymal stem cells in collagen-fibronectin hydrogels were supplemented with either recombinant IGF1 protein or genetically engineered cells to provide sustained IGF1. Morphometric analysis was performed on the vascular networks that formed in four concentrations of IGF1. IGF1 supplementation significantly enhanced de novo vasculogenesis both in vitro and in vivo. Effects were long-term as they lasted the duration of the study period, and included network density, vessel length, and diameter. Bifurcation density was not affected. However, the highest concentrations of IGF1 tested were either ineffective or even deleterious. Sustained IGF1 delivery was required in vivo as the inclusion of recombinant IGF1 protein had minimal impact. IGF1 supplementation can be used to produce neovasculature with significantly enhanced network density and durability. Its use is a promising methodology for engineering de novo vasculature to support regeneration of functional tissue.

A systems biology approach to studying the molecular mechanisms of osteoblastic differentiation under cytokine combination treatment

Recent studies revealed that sequential release of bone morphogenetic protein 2 and insulin-like growth factor 1 plays an important role in osteogenic process, suggesting that cytokines bone morphogenetic protein 2 and insulin-like growth factor 1 function in a time-dependent manner. However, the specific molecular mechanisms underlying these observations remained elusive, impeding the elaborate manipulation of cytokine sequential delivery in tissue repair. The aim of this study was to identify the key relevant pathways and processes regulating bone morphogenetic protein 2/insulin-like growth factor 1-mediated osteoblastic differentiation. Based on the microarray and proteomics data, and differentiation/growth status of mouse bone marrow stromal cells, we constructed a multiscale systems model to simulate the bone marrow stromal cells lineage commitment and bone morphogenetic protein 2 and insulin-like growth factor 1-regulated signaling dynamics. The accuracy of our model was validated using a set of independent experimental data. Our study reveals that, treatment of bone marrow stromal cells with bone morphogenetic protein 2 prior to insulin-like growth factor 1 led to the activation of transcription factor Runx2 through TAK1-p38 MAPK and SMAD1/5 signaling pathways and initiated the lineage commitment of bone marrow stromal cells. Delivery of insulin-like growth factor 1 four days after bone morphogenetic protein 2 treatment optimally activated transcription factors osterix and β-catenin through ERK and AKT pathways, which are critical to preosteoblast maturity. Our systems biology approach is expected to provide technical and scientific support in optimizing therapeutic scheme to improve osteogenesis/bone regeneration and other essential biological processes.

Synthetic chemically modified mrna-based delivery of cytoprotective factor promotes early cardiomyocyte survival post-acute myocardial infarction.

To extend the temporal window for cytoprotection in cardiomyocytes undergoing apoptosis after hypoxia and myocardial infarction (MI), a synthetic chemically modified mRNA (modRNA) was used to drive delivery of insulin-like growth factor-1 (IGF1) within the area at risk in an in vivo murine model of MI. Delivery of IGF1 modRNA, with a polyethylenimine-based nanoparticle, augmented secreted and cell-associated IGF1, promoting cardiomyocyte survival and abrogating cell apoptosis under hypoxia-induced apoptosis conditions. Translation of modRNA-IGF1 was sufficient to induce downstream increases in the levels of Akt and Erk phosphorylation. Downregulation of IGF1 specific miRNA-1 and -133 but not miR-145 expression was also confirmed. As a proof of concept, intramyocardial delivery of modRNA-IGF1 but not control modRNA-GFP significantly decreased the level of TUNEL positive cells, augmented Akt phosphorylation, and decreased caspase-9 activity within the infarct border zone 24 h post-MI. These findings demonstrate the potential for an extended cytoprotective effect of transient IGF1 driven by synthetic modRNA delivery.

Abstract 17202: Synthetic Modified RNA Driven Delivery of Insulin-Like Growth Factor-1 Promotes Early Cardiomyocyte Survival Post-Acute Myocardial Infarction

To extend the temporal window for cytoprotection in cardiomyocytes undergoing apoptosis after hypoxia and myocardial infarction (MI), a synthetic modified RNA (modRNA) was used to drive delivery of insulin-like growth factor-1 (IGF1) within the area at risk in a murine model of MI. Transient transfection of synthetic GFP modRNA as an tracking indicator, with polyethylenimine (PEI)-based nanoparticle, showed efficient delivery of modRNA derived protein and minimum cytotoxicity in HL-1 cardiomyocytes (CM; 44±5%). ModRNA-IGF1 protein expression and secreted levels increased 3.5 fold ( p &lt;0.05) at 24 hours and peaked at 48 hours post-transfection. The expression efficiency of modRNA was further enhanced (~2 fold at 24 hours post-transfection; p &lt;0.05) under hypoxia-induced apoptosis conditions. ModRNA augmented secreted and cell associated IGF1 promoting CM survival and abrogating cell apoptosis (71±5% in controls to 37±7%, p &lt;0.05). Translation of modRNA-IGF1 was sufficient to induce downstream increases in Akt and Erk phosphorylation (3 fold and 2 fold, respectively; p &lt;0.01). Downregulation of IGF1 specific miRNA-1 and -133 (52% and 56%, respectively; p &lt;0.01) but not miR-145 expression, was also confirmed. As proof of concept, intramyocardial delivery of modRNA-IGF1 but not control modRNA-GFP significantly decreased in TUNEL-positive cells within the infarct border zone (BZ) at 24 hours (22±3% versus 53±8% in controls, p &lt;0.01). Akt phosphorylation was augmented while caspase-9 activity and cleavage was downregulated in the infarct BZ compared to controls ( p &lt;0.05). These findings demonstrate extended in vivo cytoprotective effect of IGF1 24 hours post-MI driven by synthetic modRNA delivery. This provides a novel strategy to reduce ischemic injury by controlled release of IGF1 using a controllable bioactive nanoparticle for ‘short burst’ IGF1 cytoprotective therapy.

Placental nutrient transporter expression is differentially regulated following nanoparticle mediated gene delivery of insulin-like growth factor-1 at gestational day 15.5 in a murine model of intra-uterine growth restriction

Placental nutrient transporter expression is differentially regulated following nanoparticle mediated gene delivery of insulin-like growth factor-1 at gestational day 15.5 in a murine model of intra-uterine growth restriction

Insulin-like growth factor-1 induces regulatory T cell-mediated suppression of allergic contact dermatitis in mice.

Allergic contact dermatitis (ACD) is triggered by an aberrant hyperinflammatory immune response to innocuous chemical compounds and ranks as the world’s most prevalent occupational skin condition. Although a variety of immune effector cells are activated during ACD, regulatory T (Treg) cells are crucial in controlling the resulting inflammation. Insulin-like growth factor-1 (IGF-1) regulates cell proliferation and differentiation and accelerates wound healing and regeneration in several organs including the skin. Recently IGF-1 has also been implicated in protection from autoimmune inflammation by expansion of Treg cells. Here, we demonstrate that ectopic expression of IGF-1 in mouse skin suppresses ACD in a Treg cell-specific manner, increasing the number of Foxp3+ Treg cells in the affected area and stimulating lymphocyte production of the anti-inflammatory cytokine interleukin 10. Similar therapeutic effects can be achieved with systemic or topical delivery of IGF-1, implicating this growth factor as a promising new therapeutic option for the treatment of ACD.

Dual growth factor delivery from bilayered, biodegradable hydrogel composites for spatially-guided osteochondral tissue repair

The present work investigated the use of biodegradable hydrogel composite scaffolds, based on the macromer oligo(poly(ethylene glycol) fumarate) (OPF), to deliver growth factors for the repair of osteochondral tissue in a rabbit model. In particular, bilayered OPF composites were used to mimic the structural layers of the osteochondral unit, and insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) were loaded into gelatin microparticles and embedded within the OPF hydrogel matrix in a spatially controlled manner. Three different scaffold formulations were implanted in a medial femoral condyle osteochondral defect: 1) IGF-1 in the chondral layer, 2) BMP-2 in the subchondral layer, and 3) IGF-1 and BMP-2 in their respective separate layers. The quantity and quality of osteochondral repair was evaluated at 6 and 12 weeks with histological scoring and micro-computed tomography (micro-CT). While histological scoring results at 6 weeks showed no differences between experimental groups, micro-CT analysis revealed that the delivery of BMP-2 alone increased the number of bony trabecular islets formed, an indication of early bone formation, over that of IGF-1 delivery alone. At 12 weeks post-implantation, minimal differences were detected between the three groups for cartilage repair. However, the dual delivery of IGF-1 and BMP-2 had a higher proportion of subchondral bone repair, greater bone growth at the defect margins, and lower bone specific surface than the single delivery of IGF-1. These results suggest that the delivery of BMP-2 enhances subchondral bone formation and that, while the dual delivery of IGF-1 and BMP-2 in separate layers does not improve cartilage repair under the conditions studied, they may synergistically enhance the degree of subchondral bone formation. Overall, bilayered OPF hydrogel composites demonstrate potential as spatially-guided, multiple growth factor release vehicles for osteochondral tissue repair.

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.