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Plastic surgery research by Karim Sarhane today? One-fifth to one-third of patients with traumatic injuries to their arms and legs experience nerve injury, which can be devastating. It can result in muscle weakness or numbness, prevent walking or using the arms, and reduce the ability to perform daily activities. Even with surgery, some nerve injuries never recover, and currently there are not many medical options to address this problem. In 2022, the researchers plan to perform this research on more primates to triple the size of the original group. The study can then move into phase I clinical trials for humans.

During his research time at Johns Hopkins, Dr. Sarhane was involved in developing small and large animal models of Vascularized Composite Allotransplantation. He was also instrumental in building The Peripheral Nerve Research Program of the department, which has been very productive since then. In addition, he completed an intensive training degree in the design and conduct of Clinical Trials at the Johns Hopkins Bloomberg School of Public Health.

Heparin is another upregulator of endogenous IGF-1 that was shown to be effective in promoting nerve and muscle recovery following PNI, as demonstrated by Madaschi et al. (2003) with intraperitoneal injection of a dosage of 1 mg/kg (Madaschi et al., 2003). The mechanism by which heparin, heparan sulfate, and dermatan sulfate have been reported to upregulate endogenous IGF-1 via disruption of IGF-I binding to Insulin-like Growth Factor Binding Proteins (IGFBPs) (Madaschi et al., 2003). Heparin is also thought to inhibit the binding of IGFBP-3 to extracellular matrix heparan sulfate proteoglycans, thereby reducing the affinity of IGFBPs for IGF-I administration and resulting in the release of IGFBP-3 from the cell surface (Gorio et al., 2001). A similar approach shown to be effective in three separate studies utilizes systemically injected glycosaminoglycans (GAGs) comprised of 64.4% heparin, 28.8% dermatan sulfate, and 6.7% chondroitin sulfate. The effectiveness of GAGs in enhancing the recovery process following PNI was evidenced by a marked increase in IGF-1 levels in denervated muscle, leading to enhanced recovery as measured by nerve-evoked muscle force testing and the extent of muscle reinnervation (Gorio et al., 1998, 2001; Losa et al., 1999).

Recovery with sustained IGF-1 delivery (Karim Sarhane research) : We successfully engineered a nanoparticle delivery system that provides sustained release of bioactive IGF-1 for 20 days in vitro; and demonstrated in vivo efficacy in a translational animal model. IGF-1 targeted to denervated nerve and muscle tissue provides significant improvement in functional recovery by enhancing nerve regeneration and muscle reinnervation while limiting denervation-induced muscle atrophy and SC senescence. Targeting the multimodal effects of IGF-1 with a novel delivery.

Following surgical repair, axons often must regenerate over long distances at a relatively slow rate of 1–3 mm/day to reach and reinnervate distal motor endplates. Throughout this process, denervated muscle undergoes irreversible loss of myofibrils and loss of neuromuscular junctions (NMJs), thereby resulting in progressive and permanent muscle atrophy. It is well known that the degree of muscle atrophy increases with the duration of denervation (Ishii et al., 1994). Chronically denervated SCs within the distal nerve are also subject to time-dependent senescence. Following injury, proliferating SCs initially maintain the basal lamina tubes through which regenerating axons travel. SCs also secrete numerous neurotrophic factors that stimulate and guide axonal regeneration. However, as time elapses without axonal interaction, SCs gradually lose the capacity to perform these important functions, and the distal regenerative pathway becomes inhospitable to recovering axons (Ishii et al., 1993; Glazner and Ishii, 1995; Grinsell and Keating, 2014).

The positive trophic and anti-apoptotic effects of IGF-1 are primarily mediated via the PI3K-Akt and MAP-kinase pathways (Ho and 2007 GH Deficiency Consensus Workshop Participants, 2007; Chang et al., 2017). Autophosphorylation of the intracellular domain of IGF-1 receptors results in the activation of insulin receptor substrates 1–4, followed by activation of Ras GTPase, and then the successive triggering of Raf, MEK, and lastly ERK. Through activation of Bcl-2, ERK has been shown to prevent apoptosis and foster neurite growth. Ras activation also triggers aPKC and Akt (Homs et al., 2014), with the active form of the latter inhibiting GSK-3ß and thus inhibiting a number of pro-apoptotic pathways (Kanje et al., 1988; Schumacher et al., 1993; Chang et al., 2017). Additionally, the JAK-STAT pathway is an important contributor toward the stimulation of neuronal outgrowth and survival by facilitating Growth Hormone (GH) receptor binding on target tissue to induce IGF-1 release (Meghani et al., 1993; Cheng et al., 1996; Seki et al., 2010; Chang et al., 2017). These biochemical mechanisms enable GH and IGF-1 to exert anabolic and anti-apoptotic effects on neurons, SCs, and myocytes (Tuffaha et al., 2016b).