Distraction Osteogenesis for Frontosphenoidal Craniosynostosis: a Novel Surgical Treatment Modality of a Rare Suture Fusion.

Frontosphenoidal craniosynostosis (FSC) is a rare premature fusion of the frontosphenoidal suture that results in anterior plagiocephaly. When associated with severe cranial deformity, surgical treatment is beneficial. All previously reported cases of FSC correction have utilized fronto-orbital remodeling and advancement to achieve improved anatomy and increased intracranial volume. For patients with isolated synostosis deformities, we believe that distraction osteogenesis can be a viable option, with the additional benefit of quicker operating time, shorter hospital stays, and less irregularity in final head contour. This case illustrates the feasibility of using distraction osteogenesis in the management of FSC.

Pediatric Mandibular Fracture Management: Intraoperative Thermoplastic Splint Fabrication and Circummandibular Wires, without Maxillomandibular Fixation.

Management of mandibular fractures often involves the use of maxillomandibular fixation (MMF) to attain immobility of the fractured segments. This can be used as a primary treatment modality or as an adjunct in fracture management. This technique, however, has its drawbacks due to the great burden of care imposed on patients. In the following case, fixation of a pediatric open mandibular body fracture was attained without the use of MMF, and bone union was achieved. Due to age, safety concerns, long-distance travel, and parent's preference, the routine management of this type of fracture with MMF using piriform aperture drop wires and circummandibular wires was not done. Instead, the fracture was reduced, and an intraoral mandibular impression was taken in the operating room, which was used to create a stone model. A 2-mm acrylic splint was designed and fabricated from the stone model, and two circummandibular wires were placed. The wires were tightened over the acrylic splint to achieve stabilization of the mandibular reduction. At 4 weeks postoperatively, the splint was removed, and the patient was maintained on a soft diet. At 6 weeks, bone union was appreciated clinically by immobility of the mandibular segments, and the patient was advanced to a regular diet. Occlusion was corrected to premorbid state by clinical findings and 6 months postoperative imaging. This technique represents an effective approach in managing pediatric mandibular fractures when MMF cannot be used.

Modifications to the WHISTLE Flap Procedure for Correction of Secondary Cleft Lip Deformities.

Background: The whistle deformity, a deficiency of tissue in the central upper lip, is a consequential outcome of primary cleft lip repair. Among multiple described reconstructive options, the wide-hinged island swing transposition labial enhancement (WHISTLE) flap procedure by Grewal et al has been shown to be a reliable technique that restores the continuity of the orbicularis oris muscle and creates a more natural appearing tubercle and central lip element. This article aims to refine the WHISTLE flap procedure with the addition of tailored mucomuscular flaps and an upper lip-lengthening mucosal Z-plasty. Methods: A total of 11 patients with a whistle deformity were examined. All underwent the WHISTLE flap procedure with tailored mucomuscular flaps and a mucosal Z-plasty. The patients were followed for a period of from 6 to 51.5 months. Pre- and postoperative photographs were used for objective outcome comparison. Results: From 2018 to 2023, a total of 11 patients with a whistle deformity were included in the final cohort, comprised four bilateral and seven unilateral cleft lips. Ten cases (90.1%) resulted in satisfactory postoperative cosmetic appearance and did not require further interventions. A single patient with a significant preoperative discrepancy between the upper and lower lip volumes had a postoperative residual deformity. None of the patients demonstrated any functional deficits associated with the procedure. Conclusions: The WHISTLE flap procedure with the proposed individual tailoring of the mucomuscular flap and Z-plasty for mucosal scar lengthening has excellent cosmetic outcomes and can be considered as the primary treatment modality in most patients with a whistle deformity.

CD206+ tendon resident macrophages and their potential crosstalk with fibroblasts and the ECM during tendon growth and maturation.

Resident macrophages exist in a variety of tissues, including tendon, and play context-specific roles in their tissue of residence. In this study, we define the spatiotemporal distribution and phenotypic profile of tendon resident macrophages and their crosstalk with neighboring tendon fibroblasts and the extracellular matrix (ECM) during murine tendon development, growth, and homeostasis. Fluorescent imaging of cryosections revealed that F4/80+ tendon resident macrophages reside adjacent to Col1a1-CFP+ Scx-GFP+ fibroblasts within the tendon fascicle from embryonic development (E15.5) into adulthood (P56). Through flow cytometry and qPCR, we found that these tendon resident macrophages express several well-known macrophage markers, including Adgre1 (F4/80), Mrc1 (CD206), Lyve1, and Folr2, but not Ly-6C, and express the Csf1r-EGFP ("MacGreen") reporter. The proportion of Csf1r-EGFP+ resident macrophages in relation to the total cell number increases markedly during early postnatal growth, while the density of macrophages per mm2 remains constant during this same time frame. Interestingly, proliferation of resident macrophages is higher than adjacent fibroblasts, which likely contributes to this increase in macrophage proportion. The expression profile of tendon resident macrophages also changes with age, with increased pro-inflammatory and anti-inflammatory cytokine expression in P56 compared to P14 macrophages. In addition, the expression profile of limb tendon resident macrophages diverges from that of tail tendon resident macrophages, suggesting differential phenotypes across anatomically and functionally different tendons. As macrophages are known to communicate with adjacent fibroblasts in other tissues, we conducted ligand-receptor analysis and found potential two-way signaling between tendon fibroblasts and resident macrophages. Tendon fibroblasts express high levels of Csf1, which encodes macrophage colony stimulating factor (M-CSF) that acts on the CSF1 receptor (CSF1R) on macrophages. Importantly, Csf1r-expressing resident macrophages preferentially localize to Csf1-expressing fibroblasts, supporting the "nurturing scaffold" model for tendon macrophage patterning. Lastly, we found that tendon resident macrophages express high levels of ECM-related genes, including Mrc1 (mannose receptor), Lyve1 (hyaluronan receptor), Lair1 (type I collagen receptor), Ctss (elastase), and Mmp13 (collagenase), and internalize DQ Collagen in explant cultures. Overall, our study provides insights into the potential roles of tendon resident macrophages in regulating fibroblast phenotype and the ECM during tendon growth.

A simplified, amplicon-based method for whole genome sequencing of human respiratory syncytial viruses.

BACKGROUND: Human Respiratory Syncytial Virus (RSV) infections pose a significant risk to human health worldwide, especially for young children. Whole genome sequencing (WGS) provides a useful tool for global surveillance to better understand the evolution and epidemiology of RSV and provide essential information that may impact on antibody treatments, antiviral drug sensitivity and vaccine effectiveness. OBJECTIVES: Here we report the development of a rapid and simplified amplicon-based one-step multiplex reverse-transcription polymerase chain reaction (mRT-PCR) for WGS of both human RSV-A and RSV-B viruses. STUDY DESIGN: Two mRT-PCR reactions for each sample were designed to generate amplicons for RSV WGS. This new method was tested and evaluated by sequencing 206 RSV positive clinical samples collected in Australia in 2020 and 2021 with RSV Ct values between 10 and 32. RESULTS: In silico analysis and laboratory testing revealed that the primers used in the new method covered most of the currently circulating RSV-A and RSV-B. Amplicons generated were suitable for both Illumina and Oxford Nanopore Technologies (ONT) NGS platforms. A success rate of 83.5% with a full coverage for the genome of 98 RSV-A and 74 RSV-B was achieved from all clinical samples tested. CONCLUSIONS: This assay is simple to set up, robust, easily scalable in sample preparation and relatively inexpensive, and as such, provides a valuable addition to existing NGS RSV WGS methods.

Csf1 from marrow adipogenic precursors is required for osteoclast formation and hematopoiesis in bone.

Colony-stimulating factor 1 (Csf1) is an essential growth factor for osteoclast progenitors and an important regulator for bone resorption. It remains elusive which mesenchymal cells synthesize Csf1 to stimulate osteoclastogenesis. We recently identified a novel mesenchymal cell population, marrow adipogenic lineage precursors (MALPs), in bone. Compared to other mesenchymal subpopulations, MALPs expressed Csf1 at a much higher level and this expression was further increased during aging. To investigate its role, we constructed MALP-deficient Csf1 CKO mice using AdipoqCre. These mice had increased femoral trabecular bone mass, but their cortical bone appeared normal. In comparison, depletion of Csf1 in the entire mesenchymal lineage using Prrx1Cre led to a more striking high bone mass phenotype, suggesting that additional mesenchymal subpopulations secrete Csf1. TRAP staining revealed diminished osteoclasts in the femoral secondary spongiosa region of Csf1 CKOAdipoq mice, but not at the chondral-osseous junction nor at the endosteal surface of cortical bone. Moreover, Csf1 CKOAdipoq mice were resistant to LPS-induced calvarial osteolysis. Bone marrow cellularity, hematopoietic progenitors, and macrophages were also reduced in these mice. Taken together, our studies demonstrate that MALPs synthesize Csf1 to control bone remodeling and hematopoiesis.

A brief history of tendon and ligament bioreactors: Impact and future prospects.

Bioreactors are powerful tools with the potential to model tissue development and disease in vitro. For nearly four decades, bioreactors have been used to create tendon and ligament tissue-engineered constructs in order to define basic mechanisms of cell function, extracellular matrix deposition, tissue organization, injury, and tissue remodeling. This review provides a historical perspective of tendon and ligament bioreactors and their contributions to this advancing field. First, we demonstrate the need for bioreactors to improve understanding of tendon and ligament function and dysfunction. Next, we detail the history and evolution of bioreactor development and design from simple stretching of explants to fabrication and stimulation of two- and three-dimensional constructs. Then, we demonstrate how research using tendon and ligament bioreactors has led to pivotal basic science and tissue-engineering discoveries. Finally, we provide guidance for new basic, applied, and clinical research utilizing these valuable systems, recognizing that fundamental knowledge of cell-cell and cell-matrix interactions combined with appropriate mechanical and chemical stimulation of constructs could ultimately lead to functional tendon and ligament repairs in the coming decades.

Decellularization and Recellularization of Cartilage.

Decellularization of cartilage enables the use of cartilage allografts or xenografts as natural scaffolds for repair and regeneration of injured cartilage. The preservation of the extracellular matrix ultrastructure of the graft makes this a promising tool for cartilage tissue engineering. We have optimized the decellularization protocol by enzymatically digesting proteoglycans while preserving the native collagen architecture. Here we describe our methods for cartilage decellularization and cell labeling for the tracking of infiltration for recellularization in detail.

Effects of Chondroitinase ABC-Mediated Proteoglycan Digestion on Decellularization and Recellularization of Articular Cartilage.

Articular cartilage has a limited capacity to heal itself and thus focal defects often result in the development of osteoarthritis. Current cartilage tissue engineering strategies seek to regenerate injured tissue by creating scaffolds that aim to mimic the unique structure and composition of native articular cartilage. Decellularization is a novel strategy that aims to preserve the bioactive factors and 3D biophysical environment of the native extracellular matrix while removing potentially immunogenic factors. The purpose of this study was to develop a procedure that can enable decellularization and recellularization of intact articular cartilage matrix. Full-thickness porcine articular cartilage plugs were decellularized with a series of freeze-thaw cycles and 0.1% (w/v) sodium dodecyl sulfate detergent cycles. Chondroitinase ABC (ChABC) was applied before the detergent cycles to digest glycosaminoglycans in order to enhance donor chondrocyte removal and seeded cell migration. Porcine synovium-derived mesenchymal stem cells were seeded onto the decellularized cartilage scaffolds and cultured for up to 28 days. The optimized decellularization protocol removed 94% of native DNA per sample wet weight, while collagen content and alignment were preserved. Glycosaminoglycan depletion prior to the detergent cycles increased removal of nuclear material. Seeded cells infiltrated up to 100 µm into the cartilage deep zone after 28 days in culture. ChABC treatment enhances decellularization of the relatively dense, impermeable articular cartilage by reducing glycosaminoglycan content. ChABC treatment did not appear to affect cell migration during recellularization under static, in vitro culture, highlighting the need for more dynamic seeding methods.