A Tissue Engineering Approach for Prenatal Closure of Myelomeningocele with Gelatin Sponges Incorporating Basic Fibroblast Growth Factor

Abstract

Myelomeningocele (MMC) is a common and devastating malformation. Although fetal surgical closure may improve outcome, a less invasive approach that can be applied earlier in gestation is desirable. The objective of this study was to evaluate the therapeutic feasibility of a tissue engineering approach for prenatal coverage of MMC. A gelatin hydrogel composite combining a gelatin sheet and gelatin sponge was prepared with or without basic fibroblast growth factor incorporation, and applied prenatally to retinoic-acid-induced fetal MMC in the rat model. Most of the composites were adherent to the MMC within the amniotic fluid environment with the help of cyanoacrylate adhesive. Histological examination revealed cells layered over the composites with associated extracellular matrix as well as cellular ingrowth into the sponges. The layer over the composite was composed of mixed nonepithelial and epithelial cells with the extracellular matrix consisting of collagen type I and hyaluronic acid. The tissue inside the sponge consisted of nonepithelial cells and hyaluronic acid. Epidermal ingrowth underneath the sponges and neovascularization into the sponges occurred and were significantly increased by the incorporation of basic fibroblast growth factor. Although further development is needed, this study supports the therapeutic potential of a tissue engineering approach for prenatal coverage of MMC.

In utero repair of myelomeningocele with autologous amniotic membrane in the fetal lamb model

“…This would allow the CSF to continue to leak, and thus negate the beneficial effects of in utero repair on the Chiari malformation [25]. A future study could investigate the use of engineered gelatin sponges in conjunction with an AM patch as a means to promote tissue coverage as demonstrated in a rodent model of MMC by Watanabe, et al [26].…”

Intra-Amniotic Delivery of Amniotic-Derived Neural Stem Cells in a Syngeneic Model of Spina Bifida

“…For example, autologous aNSCs could be obtained by amniocenteses from a fetus with spina bifida, expanded ex vivo prenatally, and injected back into the amniotic fluid one or more times as a component of a broader therapeutic strategy to also include some form of closure of the defect at some point. Cell delivery could perhaps be combined with novel methods of defect closure, such as unique biomaterials being currently explored by different groups [25,26]. …”

Tissue Engineering Strategies for Fetal Myelomeningocele Repair in Animal Models

“…To date, experimental studies of tissue engineering approaches to prenatal repair of MMC can be divided into 2 groups according to the goals of the investigators: (1) to prevent amniotic fluid-induced neural damage by providing coverage of the defect using scaffolds [31,32,33,34,35,36,37,38] and (2) to place a scaffold and/or cells between the neural tissue and the skin repair to prevent adhesion of the repair to the cord (tethering) and/or to provide neurotrophic factors or regenerate neural tissue [39,40,41,42,43,44]. …”

“…We have initially tested our constructs using in vitro methods and subsequently applied the constructs to the retinoic acid-induced rat model of MMC using an open fetal surgical technique [31,32]. Our approach has been that if the construct appears promising in the rat model, which only allows short-term analysis (3 days), we then consider application to the sheep model of surgically created MMC to assess long-term tissue formation.…”

“…Our approach has been that if the construct appears promising in the rat model, which only allows short-term analysis (3 days), we then consider application to the sheep model of surgically created MMC to assess long-term tissue formation. Initially, we performed pilot studies and elected to use a gelatin-hydrogel construct that released basic fibroblast growth factor (bFGF) over the defect in the retinoic acid-induced fetal rat MMC model [31]. Despite the short interval of evaluation the scaffold demonstrated therapeutic potential with evidence of native fetal tissue migration, epidermal in-growth and neovascularization within and surrounding the scaffold.…”