Molecular Diagnostics and In Utero Therapeutics for Orofacial Clefts

Abstract

Orofacial clefts and their management impose a substantial burden on patients, on their families, and on the health system. Under the current standard of care, affected patients are subjected to a lifelong journey of corrective surgeries and multidisciplinary management to replace bone and soft tissues, as well as restore esthetics and physiologic functions while restoring self-esteem and psychological health. Hence, a better understanding of the dynamic interplay of molecular signaling pathways at critical phases of palate development is necessary to pioneer novel prenatal interventions. Such pathways include transforming growth factor-β (Tgfβ), sonic hedgehog (Shh), wingless-integrated site (Wnt)/β-catenin, bone morphogenetic protein (Bmp), and fibroblast growth factor (Fgf) and its associated receptors, among others. Here, we summarize commonly used surgical methods used to correct cleft defects postnatally. We also review the advances made in prenatal diagnostics of clefts through imaging and genomics and the various in utero surgical corrections that have been attempted thus far. An overview of how key mediators of signaling that drive palatogenesis are emphasized in the context of the framework and rationale for the development and testing of therapeutics in animal model systems and in humans is provided. The pros and cons of in utero therapies that can potentially restore molecular homeostasis needed for the proper growth and fusion of palatal shelves are presented. The theme advanced throughout this review is the need to develop preclinical molecular therapies that could ultimately be translated into human trials that can correct orofacial clefts at earlier stages of development.

Keywords: cleft palate; craniofacial; prenatal drug delivery; replacement therapies; signaling molecules; translational medicine.

Figure.

Small-molecule inhibitors of dickkopf (Dkk) 1 and Dkk2 (inhibitors of LRP5/6) allow for the activation of Wnt/β-catenin signaling transduction. Several different molecules have been described (e.g., WAY262611; IIIc3a) and trialed to rescue the phenotype of murine cleft models in which Dkk1/2 are upregulated in the posterior palate to the detriment of Wnt signaling.