Acute Dose-Dependent Neuroprotective Effects of Poly(pro-17β-estradiol) in a Mouse Model of Spinal Contusion Injury

17β-Estradiol (E2) confers neuroprotection in preclinical models of spinal cord injury when administered systemically. The goal of this study was to apply E2 locally to the injured spinal cord for a sustained duration using poly(pro-E2) film biomaterials. Following contusive spinal cord injury in adult male mice, poly(pro-E2) films were implanted subdurally and neuroprotection was assessed using immunohistochemistry 7 days after injury and implantation. In these studies, poly(pro-E2) films modestly improved neuroprotection without affecting the inflammatory response when compared to the injured controls. To increase the E2 dose released, bolus-releasing poly(pro-E2) films were fabricated by incorporating unbound E2 into the poly(pro-E2) films. However, compared to the injured controls, bolus-releasing poly(pro-E2) films did not significantly enhance neuroprotection or limit inflammation at either 7 or 21 days post-injury. Future work will focus on developing poly(pro-E2) biomaterials capable of more precisely releasing therapeutic doses of E2.

Vastly extended drug release from poly(pro-17β-estradiol) materials facilitates in vitro neurotrophism and neuroprotection

Central nervous system (CNS) injuries persist for years, and currently there are no therapeutics that can address the complex injury cascade that develops over this time-scale. 17β-estradiol (E2) has broad tropism within the CNS, targeting and inducing beneficial phenotypic changes in myriad cells following injury. To address the unmet need for vastly prolonged E2 release, we report first-generation poly(pro-E2) biomaterial scaffolds that release E2 at nanomolar concentrations over the course of 1-10 years via slow hydrolysis in vitro. As a result of their finely tuned properties, these scaffolds demonstrate the ability to promote and guide neurite extension ex vivo and protect neurons from oxidative stress in vitro. The design and testing of these materials reported herein demonstrate the first step towards next-generation implantable biomaterials with prolonged release and excellent regenerative potential.