Neonatal Compartment Syndrome and Compound Presentation at Birth.

Neonatal compartment syndrome is a rare condition. Early diagnosis and timely surgical intervention are paramount to optimize outcome. Time to fasciotomy is the most important prognostic factor. The purposes of this study were to describe a case presentation of neonatal compartment syndrome associated with a compound birth presentation and to perform a literature review. In this case, the neonate's fingers were noted to be present on maternal cervical examination 24 hours before delivery. The patient then was noted to have a sentinel skin lesion. A diagnosis of neonatal compartment syndrome was suspected, and she underwent urgent fasciotomy. Literature review identified a total of 60 patients from 26 studies. Most patients were managed operatively. All patients presented with a sentinel skin lesion, emphasizing the importance of this clinical sign in diagnosis. Manometry is not routinely performed and no standards are available for acceptable pressure gradients.

Differential expression of sclerostin in adult and juvenile mouse calvariae.

BACKGROUND: An understanding of the molecular mechanisms controlling bone formation is central to skeletal tissue engineering efforts. The observation that immature animals are able to heal calvarial defects while adult animals are not has proven to be a useful tool for examining these mechanisms. Thus, the authors compared expression of sclerostin, a bone inhibitor, between the calvariae of juvenile and adult mice. METHODS: Parietal bone was harvested from juvenile (6-day-old; n = 20) and adult (60-day-old; n = 20) mice. Sclerostin transcript and protein levels were compared between the parietal bone of juvenile and adult mice using polymerase chain reaction, Western blotting, and immunohistochemistry. Finally, osteoblasts from the parietal bone of juvenile and adult mice were harvested and cultured under osteogenic differentiation conditions with and without recombinant sclerostin (200 ng/ml). Terminal osteogenic differentiation was assessed at 21 days with alizarin red staining. RESULTS: Polymerase chain reaction, Western blot analysis, and immunohistochemistry all confirmed greater expression of sclerostin in the parietal bone of adult mice when compared with that of juvenile mice. Osteoblasts, whether from juvenile or adult parietal bones, demonstrated reduced capacity for osteogenic differentiation when exposed to recombinant sclerostin. CONCLUSIONS: Given the role of sclerostin in inhibiting bone formation, the authors' findings suggest that differences in expression levels of sclerostin may play a role in the differential regenerative capacity of calvariae from juvenile and adult animals. These findings suggest it as a potential target to abrogate in future tissue engineering studies.

Chemical control of FGF-2 release for promoting calvarial healing with adipose stem cells.

Chemical control of protein secretion using a small molecule approach provides a powerful tool to optimize tissue engineering strategies by regulating the spatial and temporal dimensions that are exposed to a specific protein. We placed fibroblast growth factor 2 (FGF-2) under conditional control of a small molecule and demonstrated greater than 50-fold regulation of FGF-2 release as well as tunability, reversibility, and functionality in vitro. We then applied conditional control of FGF-2 secretion to a cell-based, skeletal tissue engineering construct consisting of adipose stem cells (ASCs) on a biomimetic scaffold to promote bone formation in a murine critical-sized calvarial defect model. ASCs are an easily harvested and abundant source of postnatal multipotent cells and have previously been demonstrated to regenerate bone in critical-sized defects. These results suggest that chemically controlled FGF-2 secretion can significantly increase bone formation by ASCs in vivo. This study represents a novel approach toward refining protein delivery for tissue engineering applications.

Tissue harvest by means of suction-assisted or third-generation ultrasound-assisted lipoaspiration has no effect on osteogenic potential of human adipose-derived stromal cells.

BACKGROUND: Human adipose-derived stromal cells readily undergo osteogenic differentiation in vitro and in vivo. Thus, interest in their potential role in skeletal tissue engineering continues to escalate. Very little is known regarding the effects that energy delivered by means of third-generation ultrasound-assisted lipoaspiration may have on the osteogenic potential of these cells. The authors investigated whether differences in adipose-derived stromal cell yield, and the in vitro proliferation and osteogenic potential of these cells obtained by suction-assisted lipoaspiration or third-generation ultrasound-assisted lipoaspiration, exist. METHODS: Adipose-derived stromal cells were harvested from lipoaspiration specimens of patients undergoing elective suction-assisted lipoaspiration and third-generation ultrasound-assisted lipoaspiration. Harvested cells were seeded to evaluate proliferative capacity and in vitro osteogenic potential. Alkaline phosphatase and alizarin red staining were performed to evaluate early and terminal osteogenic differentiation, respectively. Quantitative real-time polymerase chain reaction analysis was used to examine osteogenic gene expression patterns of RUNX2/CFBA1 (early differentiation) and osteocalcin (late differentiation). RESULTS: No significant differences in the proliferative capacity (n = 3), alkaline phosphatase staining (n = 3), or extracellular matrix mineralization (n = 3) of suction-assisted lipoaspiration- or third-generation ultrasound-assisted lipoaspiration-derived cells were appreciated. Transcript levels of markers of early and terminal osteogenic differentiation were not significantly different (n = 3). CONCLUSIONS: These findings suggest that exposure of adipose-derived stromal cells to ultrasound energy during tissue harvest by means of third-generation ultrasound-assisted lipoaspiration does not impart a negative consequence toward their proliferative capacity or osteogenic potential. Thus, the cells harvested using third-generation ultrasound-assisted lipoaspiration are comparable to those obtained by means of suction-assisted lipoaspiration for use in the study of osteogenic differentiation and skeletal tissue engineering.

The role of regional posterior frontal dura mater in the overlying suture morphology.

BACKGROUND: Craniosynostosis, the premature fusion of one or more cranial sutures, is a common developmental disorder resulting in morphologic and functional consequences. The rat model is useful for studying pathologic and normal suture fusion because the posterior frontal suture undergoes fusion but the remaining sutures remain patent. The authors investigated the influence of regional posterior frontal dura mater on the overlying suture morphology and fate. METHODS: In 8-day-old Sprague-Dawley rats, an 8-mm calvarial disk was excised without disrupting the underlying dura mater (n = 22) and flipped so that the previously ectocranial aspect was adjacent to the dura mater. The animals were humanely killed after 5, 7, 9, 11, and 28 days, and the posterior frontal sutures were analyzed histologically. A comparison was made to control animals in which the disk was excised and then placed back into its anatomical position (n = 5). Immunohistochemistry of the transforming growth factor (TGF)-beta isoforms was performed to investigate their differential, temporal, and spatial expression. RESULTS: Posterior frontal suture fusion occurred on the side adjacent to the dura mater (previously patent ectocranial aspect) in an anterior-to-posterior direction, similar to that in the control group. There was specific expression of the TGF-beta isoforms in the dura mater and suture mesenchyme adjacent to the dura mater. CONCLUSIONS: Regional dura mater plays an important role in suture morphology, and the posterior frontal-associated dura mater possesses potent, pro-osteogenic signals that influence the overlying suture fate. The differential expression pattern of TGF-beta signaling from the dura mater further supports the regional paracrine effect of the dura mater.

Craniofacial surgery, from past pioneers to future promise.

OBJECTIVES: As a surgical subspecialty devoted to restoration of normal facial and calvarial anatomy, craniofacial surgeons must navigate the balance between pathologic states of bone excess and bone deficit. While current techniques employed take root in lessons learned from the success and failure of early pioneers, craniofacial surgery continues to evolve, and novel modalities will undoubtedly arise integrating past and present experiences with future promise to effectively treat craniofacial disorders. METHODS: This review provides an overview of current approaches in craniofacial surgery for treating states of bone excess and deficit, recent advances in our understanding of the molecular and cellular processes underlying craniosynostosis, a pathological state of bone excess, and current research efforts in cellular-based therapies for bone regeneration. RESULTS: The surgical treatment of bone excess and deficit has evolved to improve both the functional and morphological outcomes of affected patients. Recent progress in elucidating the molecular and cellular mechanisms governing bone formation will be instrumental for developing improved therapies for the treatment of pathological states of bone excess and deficit. CONCLUSIONS: While significant advances have been achieved in craniofacial surgery, improved strategies for addressing states of bone excess and bone deficit in the craniofacial region are needed. Investigations on the biomolecular events involved in craniosynostosis and cellular-based bone tissue engineering may soon be added to the armamentarium of surgeons treating craniofacial dysmorphologies.

Global age-dependent differences in gene expression in response to calvarial injury.

Children less than 2 years of age are capable of healing large calvarial defects, whereas adults have been found to lack this endogenous ability. In this study, we used microarray analysis to compare genomewide expression patterns during active regeneration after injury with calvaria in skeletally immature and mature mice. Parietal bone defects were created in 6-day-old (juvenile) and 60-day-old (adult) mice using a 4-mm trephine bit (n = 20 mice per age group). The calvarial disc was removed, leaving the underlying dura mater intact. Two weeks after injury, the region of regeneration with the underlying dura mater was harvested, and RNA was extracted for microarray analysis. The 25 most differentially upregulated genes in juvenile regenerates compared with adults were listed, as well as selected bone-related genes. In addition, QRT-PCR confirmation of specific genes was performed for validation. Juvenile regenerates expressed significantly greater amounts of BMP-2, -4, -7, as well as FGF-2 and its receptor FGFR-1. Various other growth factors were also noted to be upregulated, including IGF-2 and Ptn. This corresponded with the increased expression of markers for osteogenic differentiation of Sparc and Oc. Markers of osteoclast activity, Acp5, Ctsk, and Mmp2, were noted to be greater in juvenile regenerates compared with adults. The observation of Mmp14 upregulation, however, highlights the importance of balanced osteoclast-mediated bone resorption for ultimate healing. The 2 most differentially regulated genes, transthyretin (Ttr) and prostaglandin D2 synthase (Ptgds), highlight the potential role of retinoic acid signaling and the prostaglandin axis on skeletal regeneration. These findings underscore the multitude of biomolecular mechanisms at play, allowing juvenile calvaria to heal after injury. The identification of various growth factors and cytokines involved also suggests novel therapeutic strategies for tissue-engineering purposes.

Dissecting the influence of regional dura mater on cranial suture biology.

BACKGROUND: Craniosynostosis is a relatively common developmental disorder that leads to a number of serious consequences. Previous studies have shown the influence of dura mater on the overlying cranial suture. This study was conducted to determine the role of regional dura mater versus the intrinsic nature of the suture in directing the overlying suture's fate. METHODS: The authors examined the effect of regional dura mater on the fate and morphology of the posterofrontal and coronal sutures. In 8-day-old Sprague-Dawley rats, calvarial disks, consisting of the posterofrontal and coronal sutures, were excised and placed in one of three positions: (1) native position (control group), (2) rotated 45 degrees, or (3) rotated 90 degrees (n = 5 animals per group). The animals were euthanized 1 month postoperatively, and the sutures were analyzed histologically. RESULTS: The control group revealed normal suture morphology (n = 5). In the 45-degree rotation group, which placed the posterofrontal and coronal sutures over non-suture-associated dura mater, the posterofrontal sutures fused with thin morphology, and the coronal sutures remained patent (n = 5). In the 90-degree rotation group, the posterofrontal sutures, which were positioned over coronal suture-associated dura mater, were found to be fused with thinner morphology. The coronal sutures of the 90-degree rotation group, which were placed over posterofrontal suture-associated dura mater, remained patent but had acquired a posterofrontal-like morphology (n = 5). CONCLUSIONS: This study further elucidates variations in the biology of dura mater, depending on its location. Furthermore, these results illustrate the interplay between regional dura mater and the inherent characteristics of the suture complex in determining suture biology.

Cell-based therapies for skeletal regenerative medicine.

Skeletal deficits represent a substantial biomedical burden on the US healthcare system. Current strategies for reconstructing bony defects are fraught with inadequacies. Cell-based therapies for skeletal regeneration offer a paradigm shift that may provide alternative solutions. Substantial work has identified a host of cellular sources that possess the potential for osteogenic differentiation. Significant efforts have been devoted toward characterizing the role of postnatal cellular sources that are relatively abundant and easily accessible. Among these, the potential of using adipose-derived stromal cells for skeletal regeneration has garnered much interest. Integral to these efforts directed at characterizing cellular sources are studies that seek to understand the factors that initiate and regulate osteogenic differentiation of progenitor cells. Specifically, focus has been directed on elucidating the role of bone morphogenetic protein and fibroblast growth factor signaling in regulating osteogenic differentiation of osteoprogenitor cells. Concurrent studies in the field of scaffold design have also helped to advance the potential for cell-based therapies.

Microarray analysis of the role of regional dura mater in cranial suture fate.

BACKGROUND: Craniosynostosis, the premature fusion of cranial sutures, results in serious neurologic and morphologic abnormalities when left untreated. Surgical excision of the fused sutures and remodeling of the skull remains the standard therapy. Development of novel, minimally invasive therapies for craniosynostosis will undoubtedly be dependent on a more thorough understanding of the molecular mechanisms underlying this abnormality. Significant evidence suggests the influence of regional dura mater on the behavior of the overlying suture complex. The mouse model has been instrumental in investigating this observation because of the natural juxtaposition of the posterior frontal suture, which fuses early in life, with the other cranial sutures, which remain patent. METHODS: The authors used microarray analysis to compare genomic changes in the dura mater underlying the posterior frontal and sagittal sutures of mice. Suture-associated dura mater was harvested from mice before (postnatal day 5), during (postnatal day 10), and after (postnatal day 20) posterior frontal suture fusion (n = 20 mice for each of the three time points). RESULTS: Microarray results confirmed differential regulation of genes involved in paracrine signaling, extracellular matrix, and bone remodeling between the dura mater underlying the fusing posterior frontal suture and the patent sagittal suture. CONCLUSIONS: These data confirm global differences in gene expression between regional dura mater underlying fusing and patent sutures. These results provide further insight into potential molecular mechanisms that may play a role in cranial suture biology.

Mesenchymal cells for skeletal tissue engineering.

BACKGROUND: Skeletal defects represent a significant socioeconomic burden to the US healthcare system. Current options for reconstructing osseous deficits have shortcomings. OBJECTIVE: To review the use of mesenchymal stem cells for skeletal tissue engineering. METHODS: We focused on the application of mesenchymal cells in skeletal regeneration, optimization of this technique, tropic effects of multipotent mesenchymal cells, and future directions. RESULTS/CONCLUSION: A number of cell-based modalities have been investigated. We have been interested in the role of adipose-derived stromal cells in bone regeneration and understanding the mechanisms behind osteogenic differentiation of progenitor cells and acceleration of this process. Future clinical applications of multipotent mesenchymal cells will depend on better understanding of the molecular signaling involved in osteogenic differentiation and maintaining pluripotency.

Current treatment of craniosynostosis and future therapeutic directions.

Normal craniofacial development is contingent upon coordinated growth between the brain and overlying calvaria. Craniosynostosis, the premature fusion of one or more cranial sutures, perturbs this natural framework, resulting in dramatic dysmorphology of the skull and face along with a multitude of associated functional abnormalities. Traditional approaches to the treatment of craniosynostosis have employed complex surgical remodeling of the skull vault and facial deformities all aimed at increasing the amount of intracranial volume and restoring a more normal craniofacial appearance. Significant morbidity and mortality, however, have plagued these procedures, driving dramatic evolution in our approach towards the treatment of pathologically fused sutures. Recent clinical and genetic studies have identified multiple forms of human craniosynostosis, each associated with mutations within various cytokine signaling pathways. Knowledge garnered from these investigations bear promise for the future development of alternative strategies to enhance or perhaps even replace contemporary approaches for the treatment of craniosynostosis.

Cranial sutures: a brief review.

Craniosynostosis, or the premature fusion of one or more cranial sutures, is a relatively common congenital defect that causes a number of morphologic and functional abnormalities. With advances in genetics and molecular biology, research of craniosynostosis has progressed from describing gross abnormalities to understanding the molecular interactions that underlie these cranial deformities. Animal models have been extremely valuable in improving our comprehension of human craniofacial morphogenesis, primarily by human genetic linkage analysis and the development of knock-out animals. This article provides a brief review of perisutural tissue interactions, embryonic origins, signaling molecules and their receptors, and transcription factors in maintaining the delicate balance between proliferation and differentiation of cells within the suture complex that determines suture fate. Finally, this article discusses the potential implications for developing novel therapies for craniosynostosis.

Myoplasty for congenital macrostomia.

OBJECTIVE: To describe the different myoplasty techniques that could be used for limited commissural reconstruction. METHODS: Twelve cases of congenital macrostomia are reported, with different cleft lengths and termination sites. For each case, an orbicular myoplasty was performed, and in the case of extension to the area of the tragus or tonsillar pillars, a masseteric myoplasty or pharyngoplasty was performed. Functional and aesthetic results were analyzed. RESULTS: Functional results were excellent, with normal phonation, facial expression, and deglutition in the case of posterior extension. Aesthetic results were good, with only two cases of skin fasciculation during facial movement. CONCLUSIONS: Myoplasty in macrostomia could be limited to an orbicular reorientation in the case of a short cleft or can include a masseteric myoplasty or pharnygoplasty should the cleft extend further. Analyzing 90 reported cases of congenital macrostomia in the world literature, an important point has emerged. In some cases, the cleft could continue sagittally to the tonsillar pillars or laterally, distal to the anterior border of the masseter, to the region of the tragus. Repair in these cases requires reconstruction of the tonsillar pillars and masseteric repair in addition to orbicular removal. No reports in the world literature have referred to these other myoplasties that could be necessary, even if such pathology is very rare. In addition, no classification of congenital macrostomia was found in the world literature. We therefore propose a surgical classification of macrostomia relative to the nature of myoplasty required.

Applications of an athymic nude mouse model of nonhealing critical-sized calvarial defects.

Calvarial bone defects are a common clinical scenario in craniofacial surgery. Numerous approaches are used to reconstruct skull defects, and each possesses its own inherent disadvantages. This fact underscores the opportunity to develop a novel method to repair osseous defects in craniofacial surgery. Recent literature strongly suggests that cell-based therapies in the form of regenerative medicine may be a developing paradigm in reconstructive surgery. Although numerous studies have probed osteoprogenitor cells from mice, few have explored the biology of human cells in the setting of osteogenesis in an equally rigorous manner. This study proposes a nude mouse model of critical-sized calvarial defects to study the in vivo biology of human osteoprogenitor cells. Critical-sized 4.0-mm calvarial defects were created in nude mice (n = 15) with a custom trephine drill bit outfitted to a dental drill handpiece. During the craniotomy, the dura mater was spared from injury. Gross inspection, routine histology, and micro-computed tomographic scanning were performed at 2, 4, 8, and 16 weeks postoperatively. There was no calvarial healing in any of the animals by 16 weeks. The dura mater remained intact in all subjects. Gross, histologic, and radiographic assays confirmed these findings. Although several studies have implanted human osteoprogenitor cells in vivo in various animal models, few have documented the appropriate controls or conditions necessary to support the potential to translate benchtop findings into clinical applications. We propose in this study that the nude mouse critical-sized calvarial defect model will be valuable with increasing investigations with human osteoprogenitor cells.