It's - a suture or a stitch has to hold the wound closed so it has to have certain mechanical strength and imagine the problem of making something that's dissolvable so it disappears but also is strong enough to hold a wound closed reliably for a length of time.

能够拉紧切口的缝合线,就必须具有一定的机械张力,大家想像一下制造这种缝合线的难度,身体组织不仅要能吸收这种缝合线,而且这种线必须有足够的张力,一定时间内能够拉紧切口

耶鲁公开课 - 生物医学工程探索课程节选