Topographic superficial craniectomy for invasive scalp carcinoma

The management of non-melanoma skin cancer of the scalp that invades the deep structures can be challenging. An operative technique of topographic superficial craniectomy using a piezoelectric instrument (Piezosurgery (Mectron S.p.A., Carasco, Italy)) for tumours with periosteal invasion without diploic space invasion is presented here. The tumour was resected including the periosteum of the craniectomy area. A grid was carved through the outer table using the Piezosurgery device. The grid squares measured approximately 1.5 cm on each side. A bony strip was removed from one side of the grid to complete a deep cut while avoiding crossing the inner table. The squares were collected individually with a chisel and sent for pathological analysis. This technique was used to identify and localize any possible bone invasion. As this method allowed an accurate pathological diagnosis to be obtained from the Piezosurgery squares, it was possible to determine the appropriate adjuvant treatment, thereby reducing the risk of malignant cells spreading.

Polydopamine-Coated Poly(l-lactide) Nanofibers with Controlled Release of VEGF and BMP-2 as a Regenerative Periosteum

The periosteum plays an important role in vascularization and ossification during bone repair. However, in most studies, an artificial periosteum cannot restore both functions of the periosteum concurrently. In this study, a novel nanofiber that can sustain the release of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) was fabricated to enhance the durability of angiogenesis and osteogenesis during bone regeneration. A cell-free tissue engineered periosteum based on an electrospinning poly-l-lactic acid (PLLA) nanofiber was fabricated, on which VEGF and BMP-2 were immobilized through a polydopamine (PDA) coating conveniently and safely (BVP@PLLA membrane). The results indicated a significantly improved loading rate as well as a slow and sustained release of VEGF and BMP-2 with the help of the PDA coating. BMP-2 immobilized on nanofibers successfully induced the osteogenic differentiation of human bone marrow mesenchymal stem cells (BMSCs) in vitro with high expression of runt-related transcription factor 2 (Runx2), osteopontin (OPN), and alkaline phosphatase (ALP). Similarly, angiogenic differentiation of BMSCs with the expression of fetal liver kinase-1 (Flk-1) and vascular endothelial cadherin (VE-cadherin) was observed under the environment of VEGF sustained release. Moreover, an in vivo study revealed that the BVP@PLLA membrane could enhance vascular formation and new bone formation, which accelerates bone regeneration in rat femoral defects along with a massive periosteum defect. Therefore, our study suggests that the novel artificial periosteum with dual growth factor controlled release is a promising system to improve bone regeneration in bone defects along with a massive periosteum defect.

HGF/MET in osteogenic differentiation of primary human palatal periosteum-derived mesenchymal stem cells

PURPOSE

This study aimed to determine expressions of hepatocyte growth factor (HGF) and MET proto-oncogene receptor tyrosine kinase (MET) in palatal periosteum (PP) and to examine the effect of HGF/MET on osteogenic differentiation of human palatal periosteum-derived mesenchymal stem cells (PD-MSCs).

METHODS

HGF/MET proteins in human palatal periosteum (n = 3) were localized using immunohistochemistry. PD-MSCs (n = 3) were cultured in serum-free Essential 8 (E8) medium or osteogenic medium with and without Capmatinib, a selective ATP-inhibitor of MET. HGF concentration in vitro was measured with ELISA. Relative gene expression was quantified from PD-MSCs by quantitative reverse transcription real-time polymerase chain reaction.

RESULTS

Immunohistochemistry detected co-localization of HGF and MET protein in PP. HGF protein levels were significantly higher (P < 0.05) in osteogenic media (day 21: 12.19 ± 8.36 ng/mL) than in E8 medium (day 21: 0.42 ± 0.72 ng/mL). MET inhibitor had a limited feedback effect on the expression profile of the osteogenic genes tested. Gene expression levels for all but three genes were comparable in serum-free and osteogenic media at all time points.

CONCLUSION

HGF/MET present in human PP and HGF is upregulated in vitro during osteogenesis; however the targeted pathways controlled by MET may not involve osteoblast maturation.

Periosteal Flaps Enhance Prefabricated Engineered Bone Reparative Potential

The clinical translation of bone tissue engineering for reconstructing large bone defects has not advanced without hurdles. The in vivo bioreactor (IVB) concept may therefore bridge between bone tissue engineering and reconstructive surgery by employing the patient body for prefabricating new prevascularized tissues. Ideally, IVB should minimize the need for exogenous growth factors/cells. Periosteal tissues are promising for IVB approaches to prefabricate tissue-engineered bone (TEB) flaps. However, the significance of preserving the periosteal vascular supply has not been adequately investigated. This study assessed muscle IVB with and without periosteal/pericranial grafts and flaps for prefabricating TEB flaps to reconstruct mandibular defects in sheep. The sheep (n = 14) were allocated into 4 groups: muscle IVB (M group; n_M = 3), muscle + periosteal graft (MP group; n_MP = 4), muscle + periosteal flap (MVP group; n_MVP = 4), and control group (n_Control = 3). In the first surgery, alloplastic bone blocks were implanted in the brachiocephalic muscle (M) with a periosteal graft (MP) or with a vascularized periosteal flap (MVP). After 9 wk, the prefabricated TEB flaps were transplanted to reconstruct a mandibular angle defect. In the control group, the defects were reconstructed by non-prevascularized bone blocks. Computed tomography (CT) scans were performed after 13 wk and after 23 wk at termination, followed by micro-CT (µCT) and histological analyses. Both CT and µCT analysis revealed enhanced new bone formation and decreased residual biomaterial volume in the MVP group compared with control and MP groups, while the M group showed less new bone formation and more residual biomaterial. The histological analysis showed that most of the newly formed bone emerged from defect edges, but larger areas of new bone islands were found in MP and MVP groups. The MVP group showed enhanced vascularization and higher biomaterial remodeling rates. The periosteal flaps boosted the reconstructive potential of the prefabricated TEB flaps. The regenerative potential of the periosteum was manifested after the transplantation into the mechanically stimulated bony defect microenvironment.

Free Periosteal Flaps with Scaffold: An Overlooked Armamentarium for Maxillary and Mandibular Reconstruction

Simple Summary

Head and neck bone reconstruction with revascularized free periosteal flaps and scaffold is an overlooked option in the literature. Aim of the present paper was to systematically analyse the results of maxillary and mandibular reconstruction with this technique. We found a total of 7 studies with 55 patients fitting with our inclusion criteria. The overall rate of complications was 43.7%. The success rate intended as scaffold integration resulted to be 74.5%. Our paper therefore highlighted that maxillary and mandibular reconstruction with revascularized free periosteal flaps and scaffold is a possible alternative in patient unable to bone free flap complex reconstruction, with a success rate higher to that of other secondary options.

Abstract

Introduction: Head and neck bone reconstruction is a challenging surgical scenario. Although several strategies have been described in the literature, bone free flaps (BFFs) have become the preferred technique for large defects. Revascularized free periosteal flaps (FPFs) with support scaffold represents a possible alternative in compromised patient, BFF failure, or relapsing cancers as salvage treatment. However, only few clinical applications in head and neck are reported in literature. Purpose of the study was to systematically analyse the results of functional and oncologic maxillary and mandibular reconstruction with FPF with scaffold. Materials and Methods: A comprehensive review of the dedicated literature was performed according to the PRISMA guidelines searching on Scopus, PubMed/MEDLINE, Cochrane Library, Embase, Researchgate and Google Scholar databases using relevant keywords, phrases and medical subject headings (MeSH) terms. An excursus on the most valuable FPF’ harvesting sites was also carried out. Results: A total of 7 studies with 55 patients were included. Overall, the majority of the patients (n = 54, 98.1%) underwent an FPF reconstruction of the mandibular site. The most used technique was the radial forearm FPF with autologous frozen bone as scaffold (n = 40, 72.7%). The overall rate of complications was 43.7%. The success rate intended as scaffold integration resulted to be 74.5%. Conclusions: Maxillary and mandibular reconstruction with FPF and scaffold is a possible alternative in patient unfit for complex BFF reconstruction and it should be considered as a valid alternative in the sequential salvage surgery for locally advanced cancer. Moreover, it opens future scenarios in head and neck reconstructive surgery, as a promising tool that can be modelled to tailor complex 3D defects, with less morbidities to the donor site.

Periosteum-Derived Mesenchymal Stem Cells Secretome - Cell-Free Strategy for Endogenous Bone Regeneration: Proteomic Analysis in Vitro

Objectives

Millions of people worldwide are affected by diseases or injuries which lead to bone/tooth loss and defects. While such clinical situations are daily practice in most of the hospitals, the widely used treatment methods still have disadvantages. Therefore, this field of medicine is actively searching new tissue regeneration techniques, one of which could be stem cell secretome. Thus, the purpose of this research study was to perform the detail proteomic analysis of periosteum-derived mesenchymal stem cells secretome in order to evaluate if it is capable to induce osteo-regenerative process.

Material and Methods

Periosteum-derived mesenchymal stem cells (PMSCs) were extracted from adult male New Zealand White rabbits. Cells were characterised by evaluating their differentiation potential. After characterisation PMSCs secretomes were collected and their proteomic analysis was performed.

Results

PMSCs were extracted from adult male New Zealand White rabbits. In order to characterise the extracted PMSCs, they were differentiated in the directions which mainly describes MSC multipotency - osteogenic, myogenic and adipogenic. A total of 146 proteins were detected. After characterisation PMSCs secretomes were collected and their proteomic analysis was performed. The resulting protein composition indicates the ability to promote bone regeneration to fully mature bone.

Conclusions

Bioactive molecules detected in periosteum-derived mesenchymal stem cells secretome initiates the processes required for the formation of a fully functional bone.

Poly-ε-caprolactone/Whitlockite Electrospun Bionic Membrane with an Osteogenic-Angiogenic Coupling Effect for Periosteal Regeneration

The periosteum is rich in vascular networks, osteoprogenitor cells, and stem cells and plays an important role in bone defect repair. However, existing artificial periosteum materials still have difficulty in meeting clinical requirements, such as good mechanical properties and bionic structure construction, osteogenic differentiation, and vascularization capabilities. Here, a poly-ε-caprolactone (PCL)/whitlockite (WH, 5, 10, 15 wt %) artificial periosteum with different doping amounts was prepared by electrospinning technology. According to the results of in vitro mineralization experiments, the rapid ion release from WH promotes the deposition of mineralized hydroxyapatite. Inductively coupled plasma-optical emission spectroscopy, in vitro angiogenesis, and cell migration experiments showed that the bionic periosteum of the 15% WH group had the best release rate of Mg²⁺ and the best ability to promote the human umbilical vein endothelial cell angiogenesis and migration. In addition, this group promoted collagen formation and calcium deposition. Finally, the subcutaneous implantation model was used to verify the biocompatibility and angiogenesis ability of the proposed membrane in vivo. Overall, this biomimetic PCL/WH nanofiber membrane combines the positive osteogenic differentiation ability and angiogenic ability of calcium phosphate materials and thus has good application prospects in the field of periosteal repair in the future.

Peri-implant bone augmentation by the sub-periosteal peri-implant augmented layer technique and a bovine-derived bone block: A case report

BACKGROUND

When used with deproteinized bovine bone mineral (DBBM) delivered as a particulate, the sub-periosteal peri-implant augmented layer (SPAL) technique was effective in completely correcting up to 92% of peri-implant buccal bone dehiscences. The use of a DBBM block (bDBBM), however, may result in an improvement of the peri-implant bone dehiscence as well as a relevant lateral bone augmentation since its mechanical properties may ensure a better dimensional stability at flap manipulation than particulate DBBM. The aim of the present a proof-of-principle case report is to investigate if SPAL may be successfully used to obtain bone augmentation at peri-implant dehiscence sites when used with bDBBM.

CASE PRESENTATION

Lateral bone augmentation was performed using the SPAL technique at two implants showing a buccal peri-implant bone dehiscence immediately after their placement. A partial-thickness flap was elevated, leaving the periosteal layer on the buccal cortical bone plate. The periosteal layer was, in turn, elevated to create a pouch, which was used to stabilize a bDBBM graft at the peri-implant buccal bone dehiscences. At re-entry, exposed implant surfaces were completely covered by new thick hard tissue up to their most coronal portion. A free epithelial-connective tissue graft was used to augment the peri-implant soft tissue phenotype.

CONCLUSION

When used to accommodate bDBBM over the most coronal portion of an exposed implant, SPAL may successfully lead to an increase in peri-implant buccal tissue thickness.

Periosteal Tissue Engineering: Current Developments and Perspectives

Periosteum, a highly vascularized bilayer connective tissue membrane plays an indispensable role in the repair and regeneration of bone defects. It is involved in blood supply and delivery of progenitor cells and bioactive molecules in the defect area. However, sources of natural periosteum are limited, therefore, there is a need to develop tissue-engineered periosteum (TEP) mimicking the composition, structure, and function of natural periosteum. This review explores TEP construction strategies from the following perspectives: i) different materials for constructing TEP scaffolds; ii) mechanical properties and surface topography in TEP; iii) cell-based strategies for TEP construction; and iv) TEP combined with growth factors. In addition, current challenges and future perspectives for development of TEP are discussed.

Sensory Innervation of Human Bone: An Immunohistochemical Study to Further Understand Bone Pain

Skeletal diseases and their surgical treatment induce severe pain. The innervation density of bone potentially explains the severe pain reported. Animal studies concluded that sensory myelinated A∂-fibers and unmyelinated C-fibers are mainly responsible for conducting bone pain, and that the innervation density of these nerve fibers was highest in periosteum. However, literature regarding sensory innervation of human bone is scarce. This observational study aimed to quantify sensory nerve fiber density in periosteum, cortical bone, and bone marrow of axial and appendicular human bones using immunohistochemistry and confocal microscopy. Multivariate Poisson regression analysis demonstrated that the total number of sensory and sympathetic nerve fibers was highest in periosteum, followed by bone marrow, and cortical bone for all bones studied. Bone from thoracic vertebral bodies contained most sensory nerve fibers, followed by the upper extremity, lower extremity, and parietal neurocranium. The number of nerve fibers declined with age and did not differ between male and female specimens. Sensory nerve fibers were organized as a branched network throughout the periosteum. The current results provide an explanation for the severe pain accompanying skeletal disease, fracture, or surgery. Further, the results could provide more insight into mechanisms that generate and maintain skeletal pain and might aid in developing new treatment strategies. PERSPECTIVE: This article presents the innervation of human bone and assesses the effect of age, gender, bone compartment and type of bone on innervation density. The presented data provide an explanation for the severity of bone pain arising from skeletal diseases and their surgical treatment.

Comparing the chondrogenic potential of rabbit mesenchymal stem cells derived from the infrapatellar fat pad, periosteum & bone marrow

Background & objectives:

Rabbit model is commonly used to demonstrate the proof of concept in cartilage tissue engineering. However, limited studies have attempted to find an ideal source of rabbit mesenchymal stem cells (MSCs) for cartilage repair. This study aimed to compare the in vitro chondrogenic potential of rabbit MSCs isolated from three sources namely infrapatellar fat pad (IFP), periosteum (P) and bone marrow (BM).

Methods:

Rabbit MSCs from three sources were isolated and characterized using flow cytometry and multi-lineage differentiation assay. Cell proliferation was assessed using trypan blue dye exclusion test; in vitro chondrogenic potential was evaluated by histology and gene expression and the outcomes were compared amongst the three MSC sources.

Results:

MSCs from three sources shared similar morphology and expressed >99 per cent positive for CD44 and CD81 and <3 per cent positive for negative markers CD34, CD90 and human leukocyte antigen – DR isotype (HLA-DR). The BM-MSCs and IFP-MSCs showed significantly higher cell proliferation (P<0.001) than the P-MSCs from passage 4. Histologically, BM-MSCs formed a thicker cartilage pellet (P<0.01) with abundant matrix deposition than IFP and P-MSCs during chondrogenic differentiation. The collagen type 2 staining was significantly (P<0.05) higher in BM-MSCs than the other two sources. These outcomes were further confirmed by gene expression, where the BM-MSCs demonstrated significantly higher expression (P<0.01) of cartilage-specific markers (COL2A1, SOX9 and ACAN) with less hypertrophy.

Interpretation & conclusions:

This study demonstrated that BM-MSCs had superior chondrogenic potential and generated better cartilage than IFP and P-MSCs in rabbits. Thus, BM-MSCs remain a promising candidate for rabbit articular cartilage regeneration.

Biomimetic, Stiff, and Adhesive Periosteum with Osteogenic-Angiogenic Coupling Effect for Bone Regeneration

Current periosteal grafts have limitations related to low mechanical strength, tissue adhesiveness, and poor osteogenesis and angiogenesis potential. Here, a periosteum mimicking bone aid (PMBA) with similar structure and function to natural periosteum is developed by electrospinning photocrosslinkable methacrylated gelatin (GelMA), l-arginine-based unsaturated poly(ester amide) (Arg-UPEA), and methacrylated hydroxyapatite nanoparticles (nHAMA). Such combination of materials enhances the material mechanical strength, favors the tissue adhesion, and guarantees the sustained activation of nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling pathway, with well-coordinated osteogenic-angiogenic coupling effect for accelerated bone regeneration. This work presents a proof-of-concept demonstration of thoroughly considering the progression of implant biomaterials: that is, the initial material components (i.e., GelMA, Arg-UPEA, and nHAMA) equip the scaffold with suitable structure and function, while its degradation products (i.e., Ca²⁺ and l-arginine) are involved in long-term mediation of physiological activities. It is envisioned that the strategy will inspire the design of high-performance bioscaffolds toward bone and periosteum tissue engineering.

Dermal Regeneration Template and Staged Skin Grafting for Extirpative Scalp Wound Reconstruction: A 14-Year Experience

OBJECTIVE

Dermal regeneration template and staged split-thickness skin grafting may mitigate the need for flap coverage of postoncologic scalp defects. This technique has been studied previously in small case series. We examine the effect of risk factors, surgical technique, irradiation, and dressing modalities on reconstructive outcomes in a highly comorbid patient cohort.

STUDY DESIGN

Retrospective review.

SETTING

Academic medical center.

METHODS

Full- and partial-thickness extirpative scalp wounds reconstructed with dermal regeneration template and staged skin grafting were reviewed over a 14-year period. Stage 1 consisted of template application following burr craniectomy in cases lacking periosteum. Stage 2 consisted of skin grafting. Negative pressure wound therapy (NPWT) was variably used to support adherence.

RESULTS

In total, 102 patients were analyzed (average age 74, mean follow-up 18 months). Eighty-one percent were American Society of Anesthesiologists class 3 or 4. Defect size averaged 56 cm². Average skin graft take was 94.5% in full-thickness wounds. Seven patients failed this method. Preoperative scalp irradiation was associated with major complication and delayed graft healing. Comorbidities, wound size, and burring were not associated with complication. Patients were more likely to heal with NPWT compared to bolster (hazard ratio, 1.67; 95% CI 1.01-2.77; P = .046). Time between stages was 6.6 days shorter when NPWT was applied (P < .001).

CONCLUSION

Dermal template and staged skin grafting is a reliable option for postcancer scalp reconstruction in poor flap candidates. Radiotherapy is associated with adverse outcomes. Negative pressure wound therapy simplifies postoperative wound care regimens and may accelerate healing.

Heterogeneity of murine periosteum progenitors involved in fracture healing

The periosteum is the major source of cells involved in fracture healing. We sought to characterize progenitor cells and their contribution to bone fracture healing. The periosteum is highly enriched with progenitor cells, including Sca1+ cells, fibroblast colony-forming units, and label-retaining cells compared to the endosteum and bone marrow. Using lineage tracing, we demonstrate that alpha smooth muscle actin (αSMA) identifies long-term, slow-cycling, self-renewing osteochondroprogenitors in the adult periosteum that are functionally important for bone formation during fracture healing. In addition, Col2.3CreER-labeled osteoblast cells contribute around 10% of osteoblasts but no chondrocytes in fracture calluses. Most periosteal osteochondroprogenitors following fracture can be targeted by αSMACreER. Previously identified skeletal stem cell populations were common in periosteum but contained high proportions of mature osteoblasts. We have demonstrated that the periosteum is highly enriched with skeletal progenitor cells, and there is heterogeneity in the populations of cells that contribute to mature lineages during periosteal fracture healing.

A Review of Recent Developments in the Molecular Mechanisms of Bone Healing

Between 5 and 10 percent of fractures do not heal, a condition known as nonunion. In clinical practice, stable fracture fixation associated with autologous iliac crest bone graft placement is the gold standard for treatment. However, some recalcitrant nonunions do not resolve satisfactorily with this technique. For these cases, biological alternatives are sought based on the molecular mechanisms of bone healing, whose most recent findings are reviewed in this article. The pro-osteogenic efficacy of morin (a pale yellow crystalline flavonoid pigment found in old fustic and osage orange trees) has recently been reported, and the combined use of bone morphogenetic protein-9 (BMP9) and leptin might improve fracture healing. Inhibition with methyl-piperidino-pyrazole of estrogen receptor alpha signaling delays bone regeneration. Smoking causes a chondrogenic disorder, aberrant activity of the skeleton’s stem and progenitor cells, and an intense initial inflammatory response. Smoking cessation 4 weeks before surgery is therefore highly recommended. The delay in fracture consolidation in diabetic animals is related to BMP6 deficiency (35 kDa). The combination of bioceramics and expanded autologous human mesenchymal stem cells from bone marrow is a new and encouraging alternative for treating recalcitrant nonunions.

Periosteal expansion osteogenesis using an innovative, shape-memory polyethylene terephthalate membrane: An experimental study in rabbits

Periosteal expansion osteogenesis (PEO) results in the formation of new bone in the gap between periosteum and original bone. The purpose of this study is to evaluate the use of a polyethylene terephthalate (PET) membrane as an activation device. A dome-shaped PET membrane coated with hydroxyapatite/gelatin on the inner side was inserted between the elevated periosteum and bone at the rabbit calvaria. In the experimental group, the membrane was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the membrane was only inserted and fixed with titanium screw at original shape under the periosteum. After 7 days, the screw was removed and the mesh was activated in the experimental group. Three animals per group with or without setting a latency period for activation were sacrificed at 3 and 5 weeks after surgery. Bone formation was evaluated via micro-computed tomography and determined by histomorphometric methods and histological evaluation. No PET membrane-associated complications were observed during this study. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at 3 weeks after surgery. Histologically, bone formation progressed to areas adjacent to the cortical perforations; many sinusoidal vessels ran from the perforations to overlying fibrous tissue via the new bone. No bone or obvious inflammatory cells were observed over the membrane. The PET membrane has biocompatible device for PEO that induces a natural osteogenic response at the gap between the original bone and periosteum.

Thrombospondin-2 spatiotemporal expression in skeletal fractures

Fracture healing is a complex process that relies heavily on the carefully orchestrated expansion and differentiation of periosteal mesenchymal progenitor cells (MSC). Identification of new markers for periosteal MSCs is essential for the development of fracture therapeutics. Expression of the matricellular protein thrombospondin-2 (TSP2) increases during early fracture healing; however, it is currently unknown what cell population expresses TSP2. Using a TSP2 GFP reporter mouse and a stabilized murine fracture model, we characterized the expression of TSP2 during the inflammatory, soft callus formation, and hard callus formation phases of fracture healing. In addition, using TSP2 GFP positive cells harvested from reporter mouse cells, we characterized the cell population using flow cytometry and colony formation assays. In uninjured diaphyseal bone, we observed TSP2 expression in the cells located along the inner periosteum. We also observed a population of TSP2 expressing cells in undifferentiated regions of early fracture callus and along the periphery of the callus. Later in callus development, TSP2 cells were broadly distributed in the undifferentiated callus, but GFP was not expressed by chondrocytes. Flow cytometry confirmed that the majority of TSP2 expressing cells were positive for traditional murine MSC markers. Our in vitro assays further supported these findings by demonstrating all adherent and colony-forming cells expressed TSP2. Taken together, our results suggest that TSP2 is expressed by undifferentiated MSCs, but downregulated in chondrocytes. Clinical significance: expression of the matricellular protein TSP2 is a promising new marker to identify MSCs in early fracture healing.

Septal Perforation Repair Using Bilateral Rotational Flaps With Interposed Mastoid Periosteal Graft

OBJECTIVES/HYPOTHESIS

To evaluate the outcomes of endonasal repair of septal perforations utilizing opposing bilateral rotational flaps and a periosteum interposition graft.

METHODS

Retrospective review of a single surgeon, tertiary referral center experience of patients who underwent septal perforation repair. Patient demographics, etiology of perforation, closure rate, and complication data were obtained. Patients screening positively for cocaine use or anti-neutrophil cytoplasmic antibodies (ANCA) were not offered repair.

RESULTS

A total of 104 patients were included, 65 male and 39 female with mean age of 45.4 years. Etiology of perforations included prior surgery in 45, trauma in 15, and unknown in 44, and the average perforation size in each etiologic group were 1.35 cm, 1.25 cm, and 1.30 cm, respectively. The greatest dimension of perforations repaired ranged from 0.5 cm to 1.5 cm. The overall success rate was 87.5% at 6 month follow-up. Successful closure was achieved in 95.6%, 86.7%, and 79.5%, respectively (χ²  = 5.264, P = .0218).

CONCLUSION

Our described technique is a reliable endonasal approach with predictable outcomes in septal perforations up to 1.5 cm in size. Having an unknown etiology of septal perforation may be a risk factor for failure.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1497-1500, 2021.

Various Cell Therapy Approaches for Bone Diseases in the Controlled Clinical Trials: A Systematic Review and Meta-analysis Study

The objective of this review was to answer two critical questions in the cell-based bone defect therapies that were as follows: 1) does cell therapy associate with the increase in the occurrence of adverse events in the patients compared to control groups, 2) does the use of various cell therapy approaches, including More-than Minimal Manipulation (MMM) and Minimal Manipulation (MM), affect the occurrence of adverse events? An electronic literature search was performed in five databases. The controlled clinical trial studies were selected according to the eligibility criteria. Then, they were categorized into MMM and MM approaches, and a meta-analysis of the controlled clinical trials on the occurrence of adverse events was conducted. 23 controlled clinical trials, including 10 MMM (n=341 patients) and 13 MM (n=503 patients) approaches were assessed in this study. Bone defects were oral-maxillofacial defects (7MMM and 8MM), osteonecrosis of the femoral head (1MMM and 5MM), long bone shaft fracture (1MMM), and bone defect during revision total hip arthroplasty (1MMM). Cells were isolated from various tissues such as bone marrow (5MMM and 10MM), the dental pulp (2MMM and 2MM), adipose tissue (2MMM), periosteum (1MMM), and peripheral blood (1MMM). Notably, the adverse events were reported in 37 patients, and 3 patients in MMM and MM approaches, respectively. A meta-analysis demonstrated that there was no association between cell therapy and the occurrence of adverse events. Also, the MMM approach (OR: 1.46) has a higher chance of the occurrence of adverse events compared to the MM approach (OR: 0.71). These results suggested that cell therapy, specifically the MM approach, is safe to improve bone regeneration. Also, future systematic reviews should evaluate the efficacy of these cell therapy approaches.

The Bone-Forming Properties of Periosteum-Derived Cells Differ Between Harvest Sites

The development of alternatives for autologous bone grafts is a major focus of bone tissue engineering. To produce living bone-forming implants, skeletal stem and progenitor cells (SSPCs) are envisioned as key ingredients. SSPCs can be obtained from different tissues including bone marrow, adipose tissue, dental pulp, and periosteum. Human periosteum-derived cells (hPDCs) exhibit progenitor cell characteristics and have well-documented in vivo bone formation potency. Here, we have characterized and compared hPDCs derived from tibia with craniofacial hPDCs, from maxilla and mandible, respectively, each representing a potential source for cell-based tissue engineered implants for craniofacial applications. Maxilla and mandible-derived hPDCs display similar growth curves as tibial hPDCs, with equal trilineage differentiation potential toward chondrogenic, osteogenic, and adipogenic cells. These craniofacial hPDCs are positive for SSPC-markers CD73, CD164, and Podoplanin (PDPN), and negative for CD146, hematopoietic and endothelial lineage markers. Bulk RNA-sequencing identified genes that are differentially expressed between the three sources of hPDC. In particular, differential expression was found for genes of the HOX and DLX family, for SOX9 and genes involved in skeletal system development. The in vivo bone formation, 8 weeks after ectopic implantation in nude mice, was observed in constructs seeded with tibial and mandibular hPDCs. Taken together, we provide evidence that hPDCs show different profiles and properties according to their anatomical origin, and that craniofacial hPDCs are potential sources for cell-based bone tissue engineering strategies. The mandible-derived hPDCs display - both in vitro and in vivo - chondrogenic and osteogenic differentiation potential, which supports their future testing for use in craniofacial bone regeneration applications.

The Transcription Factor HAND1 Is Involved in Cortical Bone Mass through the Regulation of Collagen Expression

Temporal and/or spatial alteration of collagen family gene expression results in bone defects. However, how collagen expression controls bone size remains largely unknown. The basic helix-loop-helix transcription factor HAND1 is expressed in developing long bones and is involved in their morphogenesis. To understand the functional role of HAND1 and collagen in the postnatal development of long bones, we overexpressed Hand1 in the osteochondroprogenitors of model mice and found that the bone volumes of cortical bones decreased in Hand1^Tg/+;Twist2-Cre mice. Continuous Hand1 expression downregulated the gene expression of type I, V, and XI collagen in the diaphyses of long bones and was associated with decreased expression of Runx2 and Sp7/Osterix, encoding transcription factors involved in the transactivation of fibril-forming collagen genes. Members of the microRNA-196 family, which target the 3' untranslated regions of COL1A1 and COL1A2, were significantly upregulated in Hand1^Tg/+;Twist2-Cre mice. Mass spectrometry revealed that the expression ratios of alpha 1(XI), alpha 2(XI), and alpha 2(V) in the diaphysis increased during postnatal development in wild-type mice, which was delayed in Hand1^Tg/+;Twist2-Cre mice. Our results demonstrate that HAND1 regulates bone size and morphology through osteochondroprogenitors, at least partially by suppressing postnatal expression of collagen fibrils in the cortical bones.

Molecular Basis for Craniofacial Phenotypes Caused by Sclerostin Deletion

Some genetic disorders are associated with distinctive facial features, which can aid in diagnosis. While considerable advances have been made in identifying causal genes, relatively little progress has been made toward understanding how a particular genotype results in a characteristic craniofacial phenotype. An example is sclerosteosis/van Buchem disease, which is caused by mutations in the Wnt inhibitor sclerostin (SOST). Affected patients have a high bone mass coupled with a distinctive appearance where the mandible is enlarged and the maxilla is foreshortened. Here, mice carrying a null mutation in Sost were analyzed using quantitative micro-computed tomographic (µCT) imaging and histomorphometric analyses to determine the extent to which the size and shape of craniofacial skeleton were altered. Sost^-/- mice exhibited a significant increase in appositional bone growth, which increased the height and width of the mandible and reduced the diameters of foramina. In vivo fluorochrome labeling, histology, and immunohistochemical analyses indicated that excessive bone deposition in the premaxillary suture mesenchyme curtailed overall growth, leading to midfacial hypoplasia. The amount of bone extracellular matrix produced by Sost^-/- cells was significantly increased; as a consequence, osteoid seams were evident throughout the facial skeleton. Collectively, these analyses revealed a remarkable fidelity between human characteristics of sclerosteosis/van Buchem disease and the Sost^-/- phenotype and provide clues into the conserved role for sclerostin signaling in modulating craniofacial morphology.

TGF-β/Smad2 signalling regulates enchondral bone formation of Gli1+ periosteal cells during fracture healing

OBJECTIVES

Most bone fracture heals through enchondral bone formation that relies on the involvement of periosteal progenitor cells. However, the identity of periosteal progenitor cells and the regulatory mechanism of their proliferation and differentiation remain unclear. The aim of this study was to investigate whether Gli1-Cre^ERT2 can identify a population of murine periosteal progenitor cells and the role of TGF-β signalling in periosteal progenitor cells on fracture healing.

MATERIALS AND METHODS

Double heterozygous Gli1-CreER^T2 ;Rosa26-tdTomato^flox/wt mice were sacrificed at different time points for tracing the fate of Gli1⁺ cells in both intact and fracture bone. Gli1-CreER^T2 -mediated Tgfbr2 knockout (Gli1-CreER^T2 ;Tgfbr2^flox/flox ) mice were subjected to fracture surgery. At 4, 7, 10, 14 and 21 days post-surgery, tibia samples were harvested for tissue analyses including μCT, histology, real-time PCR and immunofluorescence staining.

RESULTS

Through cell lineage-tracing experiments, we have revealed that Gli1-Cre^{ER T2} can be used to identify a subpopulation of periosteal progenitor cells in vivo that persistently reside in periosteum and contribute to osteochondral elements during fracture repair. During the healing process, TGF-β signalling is continually activated in the reparative Gli1⁺ periosteal cells. Conditional knockout of Tgfbr2 in these cells leads to a delayed and impaired enchondral bone formation, at least partially due to the reduced proliferation and chondrogenic and osteogenic differentiation of Gli1⁺ periosteal cells.

CONCLUSIONS

TGF-β signalling plays an essential role on fracture repair via regulating enchondral bone formation process of Gli1⁺ periosteal cells.

Real-Time Imaging of CCL5-Induced Migration of Periosteal Skeletal Stem Cells in Mice

Periosteal skeletal stem cells (P-SSCs) are essential for lifelong bone maintenance and repair, making them an ideal focus for the development of therapies to enhance fracture healing.  Periosteal cells rapidly migrate to an injury to supply new chondrocytes and osteoblasts for fracture healing. Traditionally, the efficacy of a cytokine to induce cell migration has only been conducted in vitro by performing a transwell or scratch assay. With advancements in intravital microscopy using multiphoton excitation, it was recently discovered that 1) P-SSCs express the migratory gene CCR5 and 2) treatment with the CCR5 ligand known as CCL5 improves fracture healing and the migration of P-SSCs in response to CCL5. These results have been captured in real-time. Described here is a protocol to visualize P-SSC migration from the calvarial suture skeletal stem cell (SSC) niche towards an injury after treatment with CCL5. The protocol details the construction of a mouse restraint and imaging mount, surgical preparation of the mouse calvaria, induction of a calvaria defect, and acquisition of time-lapse imaging.

Identification of Functionally Distinct Mx1+αSMA+ Periosteal Skeletal Stem Cells

The periosteum is critical for bone maintenance and healing. However, the in vivo identity and specific regulatory mechanisms of adult periosteum-resident skeletal stem cells are unknown. Here, we report animal models that selectively and durably label postnatal Mx1+αSMA+ periosteal stem cells (P-SSCs) and establish that P-SSCs are a long-term repopulating, functionally distinct SSC subset responsible for lifelong generation of periosteal osteoblasts. P-SSCs rapidly migrate toward an injury site, supply osteoblasts and chondrocytes, and recover new periosteum. Notably, P-SSCs specifically express CCL5 receptors, CCR3 and CCR5. Real-time intravital imaging revealed that the treatment with CCL5 induces P-SSC migration in vivo and bone healing, while CCL5/CCR5 deletion, CCR5 inhibition, or local P-SSC ablation reduces osteoblast number and delays bone healing. Human periosteal cells express CCR5 and undergo CCL5-mediated migration. Thus, the adult periosteum maintains genetically distinct SSC subsets with a CCL5-dependent migratory mechanism required for bone maintenance and injury repair.