The objective of this study is to design a new family of biodegradable synthetic polymeric biomaterials for providing a tunable inhibition of macrophage's nitric oxide synthase (NOS) pathway. l-Arginine (Arg) is the common substrate for NOS and arginase. Both two metabolic pathways participate in the wound healing process. An impaired wound healing, such as diabetic or other chronic wounds is usually associated with an overproduction of NO by macrophages via the NOS pathway. In this study, a new family of l-nitroarginine (NOArg) based polyester amide (NOArg-PEA) and NOArg-Arg PEA copolymers (co-PEA) were designed and synthesized with different composition ratios. The NOArg-PEA and NOArg-Arg co-PEAs are biodegradable (more than 50% degradation in vitro in 4 days at 37 °C), biocompatible and did not activate the resting macrophage immune response per se. When classically activated or alternatively activated macrophages (CAM/AAM) were incubated with NOArg-PEA and NOArg-Arg co-PEAs, the treatments decreased the NO production of CAM, increased the arginase activity in both CAM and AAM, increased TGF-β1 production of CAM to various degrees and had no significant effect on TNF-α production. Diabetic rat models were used to evaluate the efficacy of NOArg-PEA and NOArg-Arg co-PEAs on wound healing. Diabetic rats treated with 2-NOArg-4 PEA, 2-NOArg-4-Arg-4 20/80, and 2-NOArg-4-Arg-4 50/50 biomaterials achieved 40%-80% faster-wound healing when compared with the control on day 7. The data from the histological and immunohistochemical analysis showed that the 2-NOArg-4-Arg-4 20/80 and 2-NOArg-4-Arg-4 50/50 treatments led to more AAM phenotypes (CD206) and arginase I production in wound tissue than the control during the first 7 days, i.e., suggesting pro-healing wound microenvironment with improved re-epithelialization of wound healing. A similar trend was retained until day 14. The 2-NOArg-4-Arg-4 20/80 and 2-NOArg-4-Arg-4 50/50 treatments also increased the collagen deposition and angiogenesis in the healing wound between day 7 and day 14. Both in vitro and in vivo data of this study showed that this new family of NOArg-Arg co-PEA biomaterials have the potential as viable alternatives for treating impaired wound healing, such as diabetic or other types of chronic wounds. STATEMENT OF SIGNIFICANCE: Diabetic or other chronic wounds is usually associated with an overproduction of NO and pro-inflammatory signals by macrophages. Arginine supplement or NOS inhibitors administration failed to achieve an expected improved wound healing because of the dynamic complexity of arginine catabolism, the difficulty in transition from pro-inflammatory to pro-healing, and the short-term efficacy. We designed and synthesized a new family of water-soluble and degradable nitroarginine-arginine polyester amides to rebalance NOS/arginase metabolism pathways of macrophages. They showed tunable immunomodulating properties in vitro. The in vivo studies were performed to evaluate their efficacy in accelerating the healing. These new biomaterials have the potential as viable alternatives for treating impaired wound healing. The general audience of Acta Biomaterialia should be interested in these findings.

中文翻译：

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具有可调节的免疫调节特性的可生物降解的基于氨基酸的聚（酯胺）及其在糖尿病大鼠伤口中的体内和体外伤口愈合研究。

这项研究的目的是设计一个新的可生物降解的合成高分子生物材料家族，以提供可调节的巨噬细胞一氧化氮合酶（NOS）途径抑制作用。1-精氨酸（Arg）是NOS和精氨酸酶的共同底物。两种代谢途径均参与伤口愈合过程。伤口愈合不良，例如糖尿病或其他慢性伤口，通常与巨噬细胞通过NOS途径产生的NO过多有关。在这项研究中，设计并合成了具有不同组成比的新系列的基于1-硝基精氨酸（NOArg）的聚酯酰胺（NOArg-PEA）和NOArg-Arg PEA共聚物（co-PEA）。NOArg-PEA和NOArg-Arg共同PEA可生物降解（在37°C下于4天内体外降解超过50％），具有生物相容性，并不能激活静止的巨噬细胞本身的免疫反应。当经典激活或替代激活的巨噬细胞（CAM / AAM）与NOArg-PEA和NOArg-Arg co-PEA孵育时，这些处理降低了CAM的NO产生，增加了CAM和AAM中的精氨酸酶活性，增加了TGF-β1的产生CAM的程度各不相同，并且对TNF-α的产生没有显着影响。使用糖尿病大鼠模型评估NOArg-PEA和NOArg-Arg co-PEA对伤口愈合的功效。与2-NOArg-4 PEA，2-NOArg-4-Arg-4 20/80和2-NOArg-4-Arg-4 50/50生物材料治疗的糖尿病大鼠相比，伤口愈合快40％-80％并在第7天进行控制。组织学和免疫组织化学分析的数据表明，2-NOArg-4-Arg-4 20/80和2-NOArg-4-Arg-4 50/50处理导致更多的AAM表型（CD206）和精氨酸酶I的产生。在开始的7天中，伤口的组织比对照组的伤口组织要多，即表明伤口微环境有利于愈合，并且伤口愈合的上皮细胞得到了改善。直到第14天都保持了类似的趋势。在第7天之间，2-NOArg-4-Arg-4 20/80和2-NOArg-4-Arg-4 50/50处理还增加了愈合伤口中的胶原沉积和血管生成。第14天。这项研究的体外和体内数据均表明，这种新的NOArg-Arg co-PEA生物材料家族具有潜力作为治疗受损伤口愈合的可行替代品，例如糖尿病或其他类型的慢性伤口。重要性声明：糖尿病或其他慢性伤口通常与巨噬细胞过量产生NO和促炎信号有关。由于精氨酸分解代谢的动态复杂性，从促炎到促愈的转变以及短期疗效，精氨酸补充剂或NOS抑制剂的给药未能实现预期的伤口愈合。我们设计并合成了水溶性和可降解硝基精氨酸-精氨酸聚酯酰胺的新家族，以重新平衡巨噬细胞的NOS /精氨酸酶代谢途径。他们在体外显示出可调节的免疫调节特性。进行了体内研究以评估其在促进愈合中的功效。这些新的生物材料具有潜在的潜力，可用于治疗受损的伤口愈合。