Differential expression of fibroblast growth factor receptors in human digital development suggests common pathogenesis in complex acrosyndactyly and craniosynostosis

The role of the fibroblast growth factor family in bone-related diseases

Fibroblast growth factor (FGF) family members are important regulators of cell growth, proliferation, differentiation, and regeneration. The abnormal expression of certain FGF family members can cause skeletal diseases, including achondroplasia, craniosynostosis syndrome, osteoarthritis, and Kashin-Beck disease. Accumulating evidence shows that FGFs play a crucial role in the growth and proliferation of bone and in the pathogenesis of certain bone-related diseases. Here, we review the involvement of FGFs in bone-related processes and diseases; FGF1 in the differentiation of human bone marrow mesenchymal stem cells and fracture repair; FGF2, FGF9, and FGF18 in osteoarthritis; FGF6 in bone and muscle injury; FGF8 in osteoarthritis and Kashin-Beck disease; and FGF21 and FGF23 on bone regulation. These findings indicate that FGFs are targets for novel therapeutic interventions for bone-related diseases.

Syndromic Craniosynostosis: Complexities of Clinical Care

Patients with syndromic craniosynostosis have a molecularly identified genetic cause for the premature closure of their cranial sutures and associated facial and extra-cranial features. Their clinical complexity demands comprehensive management by an extensive multidisciplinary team. This review aims to marry genotypic and phenotypic knowledge with clinical presentation and management of the craniofacial syndromes presenting most frequently to the craniofacial unit at Great Ormond Street Hospital for Children NHS Foundation Trust.

Developmental biology and classification of congenital anomalies of the hand and upper extremity

Recent investigations into the mechanism of limb development have clarified the roles of several molecules, their pathways, and interactions. Characterization of the molecular pathways that orchestrate limb development has provided insight into the etiology of many limb malformations. In this review, we describe how the insights from developmental biology are related to clinically relevant anomalies and the current classification schemes used to define, categorize, and communicate patterns of upper limb malformations. We advocate an updated classification scheme for upper limb anomalies that incorporates our current molecular perspective of limb development and the pathogenetic basis for malformations using dysmorphology terminology. We anticipate that this scheme will improve the utility of a classification as a basis for diagnosis, treatment, and research.

Advances in the molecular pathogenesis of craniofacial conditions

The impact that the understanding of fibroblast growth factor receptor (FGFR) biology and its relevance to the pathogenesis of the craniosynostoses has made cannot be underestimated. As the genetic and molecular pathology of other conditions become increasingly understood, there is much hope that robust and relevant animal models of these conditions may be generated. From these models-and in conjunction with laboratory studies in vitro-comes a real hope of improved therapeutic strategies. The future lies in increased cooperation between clinicians working in high-volume centers and basic scientists. This article decribes the results of a decade of research in which the molecular pathology of the craniosynostoses was unravelled. The understanding of the importance of FGFR mutations to the genetic etiology of craniosynostosis opened up novel studies in developmental biology in various tissues. Such studies describe the functional effects of FGFR mutations. Investigations of FGFR expression in human craniofacial development have related functional molecular studies to human craniosynostosis syndromes, which provides a link between the gene mutation and the affected child.

Allogreffe de main chez le nouveau-né agénésique: étude de faisabilité

Would a newborn with a single hand benefit from hand allograft? Transantebrachial aplasia is the chosen clinical form of agenesia in our interrogation. The feasibility study presents several aspects: 1) ethical and psychological aspects. Is this a desired surgery for agenesic population? Which are the functional, psychological and social situations of agenesic patient? Is the hand transplantation in newborn ethically acceptable? What is the parents' attitude toward agenesia? Can we envisage organ donation in neonatal period? 2) immunological aspects. The non-vital character of this condition and its' good functional tolerance cannot make accepting the risk of adverse effects of hand allotransplantation. Hence, one may consider this surgery only without immunosuppression. Can the peculiarities of the neonate "immature" immune system represent an opportunity of easier tolerance obtaining, avoiding immunosuppression? 3) anatomical and technical aspects. The proximal tissues at the level of amputation are all hypoplastic in agenesic patients. Can we efficaciously suture those structures with donor eutrophic tissues? 4) cognitive aspects. Is a neonate born with only one hand is able to use two? A feasibility study on such a subject needs to take into account all these aspects. This research is useful because, even if hand allograft in agenesic newborn will never be done, the provided information will allow to progress in the vaster domain of composite tissue allotransplantation in perinatology.

Expression of FGFR-2 and FGFR-3 in the normal human fetal orbit

AIMS

To demonstrate the expression patterns of two fibroblast growth factor receptors (FGFR-2 and FGFR-3) in the normal human fetal orbit.

METHODS

6 microm orbital slide sections were prepared from 12 week old human fetal material obtained within established ethical guidelines. Radioactive in situ hybridisation techniques were used to demonstrate the expression patterns of FGFR-2 and FGFR-3 within these sections. Only one foetus had appropriate orbital sections taken.

RESULTS

FGFR-2 was expressed within the extraocular muscles (EOMs) and the optic nerve sheath and to a lesser degree within the orbital periosteal margins and the cranial sutures. FGFR-3 was expressed a lot within the periosteal margins and cranial sutures but not within either the EOMs or the optic nerve sheath.

CONCLUSIONS

FGFR-2 and FGFR-3 are differentially expressed within different orbital components. FGFR-2 gene mutations may be responsible for craniosynostotic syndromes such as Crouzon, Pfeiffer, and Apert, while those in the FGFR-3 gene may cause isolated unicoronal synostosis. EOMs may be histologically abnormal in cases of Apert, Pfeiffer, and Crouzon syndromes but not isolated unicoronal synostosis. The pattern of expression of FGFR-2 in the normal human fetal orbit may explain some of the EOM histological findings seen in some cases of Apert, Pfeiffer, and Crouzon syndromes.

Apoptosis and plastic surgery

Apoptosis, or programmed cell death, is a phenomenon that is integral to development and cellular homeostasis. In the last decade, many of the essential molecules and pathways that control this phenomenon have been elucidated. Because apoptosis is involved in almost all physiologic and pathologic processes, the understanding of its regulation has significant clinical ramifications. This article reviews the basic understanding of programmed cell death in terms of the effector molecules and pathways. Areas of interest to plastic surgeons are reviewed as they pertain to apoptosis. These areas include allotransplantation, craniofacial and limb development, flap survival, wound healing, stem cell science, and physiologic aging. These topics have not yet been studied extensively in the context of cell death. In this review article, other related and more comprehensively studied scientific areas are used to extrapolate their relevance to apoptosis. Apoptosis is an increasingly better understood process. With the knowledge of how programmed cell death is controlled, combined with the improved ability to effectively perform genetic manipulation and to design specific chemical approaches, apoptosis is gaining clinical relevance. In the next few years, practical clinical breakthroughs will help the medical community to understand the phenomenon of apoptosis and how it relates to the needs of patients.

FGF18 is required for normal cell proliferation and differentiation during osteogenesis and chondrogenesis

Fibroblast growth factor (FGF) signaling is involved in skeletal development of the vertebrate. Gain-of-function mutations of FGF receptors (FGFR) cause craniosynostosis, premature fusion of the skull, and dwarfism syndromes. Disruption of Fgfr3 results in prolonged growth of long bones and vertebrae. However, the role that FGFs actually play in skeletal development in the embryo remains unclear. Here we show that Fgf18 is expressed in and required for osteogenesis and chondrogenesis in the mouse embryo. Fgf18 is expressed in both osteogenic mesenchymal cells and differentiating osteoblasts during calvarial bone development. In addition, Fgf18 is expressed in the perichondrium and joints of developing long bones. In calvarial bone development of Fgf18-deficient mice generated by gene targeting, the progress of suture closure is delayed. Furthermore, proliferation of calvarial osteogenic mesenchymal cells is decreased, and terminal differentiation to calvarial osteoblasts is specifically delayed. Delay of osteogenic differentiation is also observed in the developing long bones of this mutant. Conversely, chondrocyte proliferation and the number of differentiated chondrocytes are increased. Therefore, FGF18 appears to regulate cell proliferation and differentiation positively in osteogenesis and negatively in chondrogenesis.

From genotype to phenotype: the differential expression of FGF, FGFR, and TGFbeta genes characterizes human cranioskeletal development and reflects clinical presentation in FGFR syndromes

Mutations in the fibroblast growth factor receptor (FGFR) genes 1, 2, and 3 are causal in a number of craniofacial dysostosis syndromes featuring craniosynostosis with basicranial and midfacial deformity. Great clinical variability is displayed in the pathologic phenotypes encountered. To investigate the influence of developmental genetics on clinical diversity in these syndromes, the expression of several genes implicated in their pathology was studied at sequential stages of normal human embryo-fetal cranial base and facial ossification (n = 6). At 8 weeks of gestation, FGFR1, FGFR2, and FGFR3 are equally expressed throughout the predifferentiated mesenchyme of the cranium, the endochondral skull base, and midfacial mesenchyme. Both clinically significant isoforms of FGFR2, IgIIIa/c and IgIIIa/b, are coexpressed in maxillary and basicranial ossification. By 10 to 13 weeks, FGFR1 and FGFR2 are broadly expressed in epithelia, osteogenic, and chondrogenic cell lineages. FGFR3, however, is maximally expressed in dental epithelia and proliferating chondrocytes of the skull base, but poorly expressed in the osteogenic tissues of the midface. FGF2 and FGF4, but not FGF7, and TGFbeta1 and TGFbeta3 are expressed throughout both osteogenic and chondrogenic tissues in early human craniofacial skeletogenesis. Maximal FGFR expression in the skull base proposes a pivotal role for syndromic growth dysplasia at this site. Paucity of FGFR3 expression in human midfacial development correlates with the relatively benign human mutant FGFR3 midfacial phenotypes. The regulation of FGFR expression in human craniofacial skeletogenesis against background excess ligand and selected cofactors may therefore play a profound role in the pathologic craniofacial development of children bearing FGFR mutations.