*Article* **Cloning, Expression and E**ff**ects of** *P. americana* **Thymosin on Wound Healing**

**Jie Jing 1, Xiaohong Sun 1, Chuang Zhou 1, Yifan Zhang 1, Yongmei Shen 2, Xiaomao Zeng 3, Bisong Yue 1 and Xiuyue Zhang 4,\***


Received: 25 August 2019; Accepted: 3 October 2019; Published: 5 October 2019

**Abstract:** The American cockroach (*Periplaneta americana*) is a medicinal insect. Its extract is used clinically to promote wound healing and tissue regeneration, but the effective medicinal components and mechanisms are not ye<sup>t</sup> clear. It has been reported that human thymosin beta 4 (Tβ4) may accelerate skin wound healing, however, the role of *P. americana* thymosin (Pa-THYs) is still poorly understood. In the present study, we identify and analyze the DNA sequences of Pa-THYs by bioinformatics analysis. Then we clone, express, and purify the Pa-THYs proteins and evaluate the activity of recombinant Pa-THYs proteins by cell migration and proliferation assays in NIH/3T3 cells. To elucidate the role of Pa-THYs in wound healing, a mouse model is established, and we evaluate wound contraction, histopathological parameters, and the expressions of several key growth factors after Pa-THYs treatment. Our results showed that three THY variants were formed by skipping splicing of exons. Pa-THYs could promote fibroblast migration, but have no effect on fibroblast proliferation. In wound repair, Pa-THYs proteins could effectively promote wound healing through stimulating dermal tissue regeneration, angiogenesis, and collagen deposition. On the molecular mechanism, Pa-THYs also stimulated the expression of several key growth factors to promote wound healing. The data sugges<sup>t</sup> that Pa-THYs could be a potential drug for promoting wound repair.

**Keywords:** *Periplaneta americana*; multimeric thymosin; prokaryotic expression; wound healing
