Bioengineering and in utero transplantation of fetal skin in the sheep model: A crucial step towards clinical application in human fetal spina bifida repair

Abstract

An intricate problem during open human fetal surgery for spina bifida regards back skin closure, particularly in those cases where the skin defect is much too large for primary closure. We hypothesize that tissue engineering of fetal skin might provide an adequate autologous skin substitute for in utero application in such situations. Eight sheep fetuses of four time-mated ewes underwent fetoscopic skin biopsy at 65 days of gestation. Fibroblasts and keratinocytes isolated from the biopsy were used to create fetal dermo-epidermal skin substitutes. These were transplanted on the fetuses by open fetal surgery at 90 days of gestation on skin defects (excisional wounds) created during the same procedure. Pregnancy was allowed to continue until euthanasia at 120 days of gestation. The graft area was analyzed macroscopically and microscopically. The transplanted fetal dermo-epidermal skin substitutes was well discernable in situ in three of the four fetuses available for analysis. Histology confirmed healed grafts with a close to natural histological skin architecture four weeks after in utero transplantation. This experimental study generates evidence that laboratory grown autologous fetal skin analogues can successfully be transplanted in utero. These results have clinical implications as an analogous procedure might be applied in human fetuses undergoing prenatal repair to facilitate primary skin closure. Finally, this study may also fertilize the field of fetal tissue engineering in general, particularly when more interventional, minimallyinvasive, and open fetal surgical procedures become available.

Large Animal Models in Regenerative Medicine and Tissue Engineering: To Do or Not to Do

“…The skin substitute, made of hydrogel colonized by autologous fibroblasts and keratinocytes, was transplanted in utero. The skin substitutes showed a normal histology after 1 month (Mazzone et al, 2020).…”

“…In a similar ovine wound model, Liebsch et al (2018) applied native spider silk as a wound dressing to test its biocompatibility and regenerative capacities ( Liebsch et al, 2018 ). Mazzone et al (2020) used bioengineered autologous skin substitutes to treat myelomeningocele in a spina bifida repair model. The skin substitute, made of hydrogel colonized by autologous fibroblasts and keratinocytes, was transplanted in utero.…”

The influence of CD26+ and CD26− fibroblasts on the regeneration of human dermo-epidermal skin substitutes

“…Human fetal fibroblasts were extracted from fetal skin samples, as described previously in 37 . Human postnatal dermal fibroblasts and keratinocytes were isolated and expanded from foreskin samples, as described previously 21 , 38 .…”

Magnetically Assisted Robotic Fetal Surgery for the Treatment of Spina Bifida

“…The constraints of in utero procedures render their method impractical for our application. In our experimental settings, we adopted an alternative approach inspired by [27]- [29], where we simulated the future use of a personalised bioengineered autologous skin-cartilage composite graft using a collagen patch to cover the back lesion [29]- [31]. To bond the patch to the skin of the fetus and seal the lesion, we followed the procedure demonstrated in [29], where the collagen patch edge is locally molten and bonded to the fetus skin using a laser.…”