It is difficult for traditional sutures, which are usually braided by microfibers, to load drugs or growth factors. To develop a novel species of suture, in this study, a core-sheath yarn was fabricated by surrounding Poly (lactic-co-glycolic acid) (PLGA) microfibers with electrospun PLGA nanofibers using a custom electrospinning equipment with two needles and a rotating funnel. The resulting yarn shows enough mechanical strength to be used as sutures. The capillary action, which is caused by the structure of the core-sheath yarn, enabled the PLGA yarn to easily absorb a growth factor. Thus TGF-beta 1 was loaded to the core-sheath yarn ensuring that the suture has a tissue repairing function. Human umbilical vein endothelial cells grew faster on TGF-beta 1 loaded core-sheath yarn than on the core-sheath yarn without growth factor. This core-sheath yarn fabrication method has the potential to be used in the development of functional sutures. (C) 2017 Elsevier B.V. All rights reserved.