Peripheral nerve regeneration research with Karim Sarhane right now

Plastic surgery research from Karim Sarhane today? We performed a study with rodents and primates that showed this new delivery method provided steady release of IGF-1 at the target nerve for up to 6 weeks,” Dr. Karim Sarhane reported. Compared to animals without this hormone treatment, IGF-1 treated animals (rodents and primates) that were injected every 6 weeks showed a 30% increase in nerve recovery. This has the potential to be a very meaningful therapy for patients with nerve injuries. Not only do these results show increased nerve recovery but receiving a treatment every 6 weeks is much easier on a patient’s lifestyle than current available regiments that require daily treatment.

Dr. Karim Sarhane is an MD MSc graduate from the American University of Beirut. Following graduation, he completed a 1-year internship in the Department of Surgery at AUB. He then joined the Reconstructive Transplantation Program of the Department of Plastic and Reconstructive Surgery at Johns Hopkins University for a 2-year research fellowship. He then completed a residency in the Department of Surgery at the University of Toledo (2021). In July 2021, he started his plastic surgery training at Vanderbilt University Medical Center. He is a Diplomate of the American Board of Surgery (2021).

Although numerous studies have demonstrated the benefit of IGF-1 to SCs, myocytes, and neurons in vitro and following PNI in animal models, several factors must be examined prior to proposing a treatment modality that is suitable for clinical translation. Besides efficacy, additional considerations include ease of regulatory clearance and safety. With regard to regulatory clearance, GH, Growth Hormone Releasing Hormone, and IGF-1 are already clinically available, FDA-approved drugs approved for other indications. With regards to safety, hypoglycemia is the most commonly seen short-term effect of IGF-1 use, although accumulation of body fat, coarsening of facial features, and lymphoid hyperplasia necessitating surgical correction have also been observed with long-term use (Contreras et al., 1995; Tuffaha et al., 2016b). Clinical trials investigating a link between malignancy and exogenous GH therapy have been equivocal, with multiple studies in children undergoing GH therapy demonstrating a low risk of associated malignancy. Additionally, GH therapy in adults has not been found to increase the risk of cancer (Yang et al., 2004; Xu et al., 2005; Chung et al., 2008; Renehan and Brennan, 2008; Svensson and Bengtsson, 2009; Tuffaha et al., 2016b). Given the potential systemic effects of IGF-1, a practical delivery system that can provide sustained release of bioactive IGF-1 to nerve and muscle tissue affected by PNI is of great importance. It will also be important to determine the minimum dose and duration required to achieve therapeutic efficacy.

Effects 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.

The amount of time that elapses between initial nerve injury and end-organ reinnervation has consistently been shown to be the most important predictor of functional recovery following PNI (Scheib and Hoke, 2013), with proximal injuries and delayed repairs resulting in worse outcomes (Carlson et al., 1996; Tuffaha et al., 2016b). This is primarily due to denervation-induced atrophy of muscle and Schwann cells (SCs) (Fu and Gordon, 1995).

Insulin-like growth factor-1 (IGF-1) is a particularly promising candidate for clinical translation because it has the potential to address the need for improved nerve regeneration while simultaneously acting on denervated muscle to limit denervation-induced atrophy. However, like other growth factors, IGF-1 has a short half-life of 5 min, relatively low molecular weight (7.6 kDa), and high water-solubility: all of which present significant obstacles to therapeutic delivery in a clinically practical fashion (Gold et al., 1995; Lee et al., 2003; Wood et al., 2009). Here, we present a comprehensive review of the literature describing the trophic effects of IGF-1 on neurons, myocytes, and SCs. We then critically evaluate the various therapeutic modalities used to upregulate endogenous IGF-1 or deliver exogenous IGF-1 in translational models of PNI, with a special emphasis on emerging bioengineered drug delivery systems. Lastly, we analyze the optimal dosage ranges identified for each mechanism of IGF-1 with the goal of further elucidating a model for future clinical translation.