Fetal Tissue Engineering to Treat Spina Bifida Before Birth

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ABSTRACT Spina bifida (SB) is the most common cause of lifelong childhood paralysis in the United States, and approximately four children are born with this devastating neurological congenital defect daily. SB results from the incomplete closure of the neural tube during the fourth week of gestation, leaving the delicate nervous tissue of the spinal cord unprotected by the typical layers of bone and connective tissue. The exposed spinal cord sustains intrauterine chemical and mechanical trauma, leaving children with lifelong paralysis, bowel and bladder incontinence, musculoskeletal deformities, and cognitive disabilities due to hindbrain herniation. Until recently, there was no treatment of SB and postnatal surgical closure of the exposed spinal cord, dura and skin was primarily intended to prevent infection of the cerebrospinal fluid (meningitis). The treatment paradigm changed after the NIH funded Management of Myelomeningocele Study (MOMS) - a multicenter, prospective, randomized, controlled clinical trial - demonstrated that in utero repair of the SB defect was safe, decreased the risk of hindbrain herniation and the need for CSF shunting, and that patients showed improvement in distal neurologic function. While promising, the motor function improvements seen in the MOMS trial were limited, and 58% of children who underwent prenatal repair were still unable to walk independently. Our recent preclinical studies showed that treatment with early gestation placental derived mesenchymal stromal cells (PMSCs) during in utero repair cures SB-associated motor function at birth in a fetal lamb model. However, we also found that while treating the SB lesion with PMSCs at the time of standard in utero surgical repair rescued motor function, locomotor recovery declined over time after birth in the fetal lamb model. Detailed radiological and histological analyses showed that locomotor function decreased after the development of severe kyphosis, cord compression and tethering due to the lack of bone and connective tissue, which is consistent with human clinical findings. In this study, we propose to develop a multifunctional, bioengineered scaffold to provide neuroprotection, anti-tethering and bone regeneration functions in one treatment to solve this complicated disease problem. Our central hypothesis is that in utero transplantation of a multifunctional bioengineered scaffold that utilizes the unique fetal developmental environment will provide a comprehensive treatment to the disease development and cure SB before birth. If successfully accomplished, this therapy will significantly lower healthcare costs and improve the quality of life of patients with SB.