Scaffolds from alternating block polyurethanes of poly(E-caprolactone) and poly(ethylene glycol) with stimulation and guidance of nerve growth and better nerve repair than autograft Yuqing Niu, 1 * Linjing Li, 1 * Kevin C. Chen, 1 Feiran Chen, 2 Xiangyu Liu, 1 Jianfu Ye, 1 Wei Li, 3 Kaitian Xu 4 1 Multidisciplinary Research Center, Shantou University, Daxue Lu 243, Shantou, Guangdong 515063, China 2 Department of Chemistry, Jinan University, Guangzhou 510632, China 3 Department of Neurosurgery, the First Affiliated Hospital, Jinan University, Guangzhou 510630, China 4 Department of Materials Science and Engineering, Jinan University, Guangzhou 510632, China Received 24 June 2014; accepted 16 November 2014 Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.a.35372 Abstract: Nerve repair scaffolds from novel alternating block polyurethanes (PUCL-alt-PEG) based on PCL and PEG without additional growth factors or proteins were prepared by a par- ticle leaching method. The scaffolds have pore size 10220 mm and porosity 92%. Mechanical tests showed that the poly- urethane scaffolds have maximum loads of 5.97 6 0.35 N and maximal stresses of 8.84 6 0.5 MPa. Histocompatiblity of the nerve repair scaffolds was tested in a SD rat model for peripheral nerve defect treatment. Two types of treatments including PUCL-alt-PEG scaffolds and autografts were com- pared in rat model. After 32 weeks, bridging of a 12 mm defect gap by the regenerated nerve was observed in all rats. The nerve regeneration was systematically characterized by sciatic function index (SFI), electrophysiology, histological assessment including HE staining, immunohistochemistry, ammonia sliver staining, Masson’s trichrome staining and TEM observation. Results revealed that nerve repair scaffolds from PUCL-alt-PEG exhibit better regeneration effects com- pared to autografts. Electrophysiological recovery was seen in 90% and 87% of rats in PUCL-alt-PEG and autograft groups respectively. Biodegradation in vitro and in vivo shows good degradation match of PUCL-alt-PEG scaffolds with nerve regeneration. It demonstrates that plain nerve repair scaffolds from PUCL-alt-PEG biomaterials can achieve peripheral nerve regeneration satisfactorily. V C 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 00A:000–000, 2014. Key Words: alternating block polyurethanes, poly(E-caprolac- tone) (PCL), poly(ethylene glycol) (PEG), scaffold, periphery nerve repair How to cite this article: Niu Y, Li L, Chen KC, Chen F, Liu X, Ye J, Li W, Xu K. 2014. Scaffolds from alternating block polyur- ethanes of poly(E-caprolactone) and poly(ethylene glycol) with stimulation and guidance of nerve growth and better nerve repair than autograft. J Biomed Mater Res Part A 2014:00A:000–000. INTRODUCTION Large-gap peripheral nerve defect is a very common clinical trauma and often leads to permanent disability of feeling and movement functions in patients. 1–3 Transplantation of autologous nerve graft has typically been used for the repair of injured peripheral nerve as a first line therapy. However, there are many disadvantages with this method including mismatch between defect nerve and graft nerve diameter, second surgical step for the extraction of donor nerve, shortage supply of donor graft, donor site morbidity, inad- equate return of function, aberrant regeneration, and so on. 4–6 Because of the host immunogenicity rejection to the donor graft, the method of use of allograft achieves few suc- cesses in clinical practice. 3,7 Comorbidity of harvesting donor graft hinders development of the muscle and vein grafts in repair of severed peripheral nerves. 3,8,9 Further- more, none of these surgery approaches has resulted in axo- nal connections. However, an alternative approach is to use a nerve repair scaffold serving both to promote nerve regeneration and to provide a pathway for nerve outgrowth. Biodegradable polyurethanes have been used as biomate- rials for many years because of their excellent mechanical, processing properties, and adequate biocompatibility. 10–13 We achieved a class of novel biomaterials called alternating block polyurethanes (PU-alt), which possesses well-controlled and determined chemical structures as well as regular microstruc- tures. The regular structures endow materials with more spe- cial and intriguing properties, such as better biocompatibility, mechanical, and shape forming properties, giving us capability for more sophisticated applications. 14 Series of alternating block polyurethanes were synthesized by incorporating various biodegradable blocks, such as polycaprolactone *The authors contributed equally to this work. Correspondence to: K. Xu; e-mail: txukaitian@jnu.edu.cn or W. Li; e-mail: tliwei@jnu.edu.cn V C 2014 WILEY PERIODICALS, INC. 1