Obliteration of the pulp canal caused by mandibular distraction: a case report

We present a 16-year-old boy with a history of ankylosis of the temporomandibular joint (TMJ) who had been treated with a costochondral graft and mandibular distraction. The distraction seems to have caused pulp canal obliteration of the lower right second premolar and lower right first molar on radiographic examination. To our knowledge this is the only reported instance of such damage related to mandibular distraction. We aim to highlight the risks of this complication and the importance of discussing it with patients as part of the process of informed consent.     

Characterization of the chondrogenic and osteogenic potential of male and female human muscle‐derived stem cells: Implication for stem cell therapy

People of all backgrounds are susceptible to bone and cartilage damage, and these injuries can be debilitating. Current treatments for bone and cartilage injuries are less than optimal, and we are interested in developing new approaches to treat these diseases, specifically using human muscle‐derived stem cells (hMDSCs). Our lab previously demonstrated that sex differences exist between male and female murine MDSCs; thus, this paper sought to investigate whether sex differences also exist in hMDSCs. In the present study, we characterized the chondrogenic and osteogenic sex differences of hMDSCs in vitro and in vivo. We performed in vitro osteogenic and chondrogenic differentiation using hMDSC pellet cultures. As demonstrated by microCT, histology, and immunohistochemistry, male hMDSCs were more chondrogenic and osteogenic than their female counterparts in vitro. No differences were observed based on the sex of hMDSCs in osteogenic and chondrogenic gene expression and cell surface markers. For our in vivo study, we transduced hMDSCs with lenti‐BMP2/GFP and transplanted these cells into critical‐sized calvarial defects in mice. MicroCT results revealed that male hMDSCs regenerated more bone at 2 weeks and demonstrated higher bone density at 4 and 6 weeks than female hMDSCs. Histology demonstrated that both male and female hMDSCs regenerated functional bone. Clinical relevance: These studies reinforce that stem cells isolated from male and female patients differ in function, and we should disclose the sex of cells used in future studies. Considering sex differences of hMDSCs may help to improve cell‐based therapies for autologous cell treatment of bone and cartilage damage. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1339–1349, 2019.     

The accuracy of virtual-surgical-planning-assisted treatment of hemifacial microsomia in adult patients: distraction osteogenesis vs. orthognathic surgery

Hemifacial microsomia (HFM) is a common congenital craniofacial deformity with a high prevalence. Orthognathic surgery and distraction osteogenesis are two conventionally used treatments of HFM. The main objective of this retrospective study was to evaluate the accuracy of two treatments with the help of virtual surgical planning in adult HFM patients. Sixty-eight adult patients with unilateral HFM were enrolled in this study. Preoperative surgical planning and simulation were performed on three-dimensional computed tomography models. Orthognathic surgery or distraction osteogenesis was performed under the guidance of three-dimensional surgical templates. Postoperative evaluation of the intervention was performed by comparison of the affected ramus height, chin deviation and the occlusal cant in surgical planning and actual result. Outcome and feedback information (an average of 14 months) showed that virtual surgical planning was accurately transferred to actual surgery in both surgical approaches. There were no statistical differences between the accuracy of affected ramus height and the occlusal cant in two surgical approaches. The orthognathic group showed significantly higher accuracy in chin deviation. In conclusion, virtual surgical planning and three-dimensional surgical templates were proved to facilitate treatment planning and offer an accurate surgical result in the treatment of adult HFM patients.     

The effects of dynamic compressive loading on human mesenchymal stem cell osteogenesis in the stiff layer of a bilayer hydrogel

Bilayer hydrogels with a soft cartilage‐like layer and a stiff bone‐like layer embedded with human mesenchymal stem cells (hMSCs) are promising for osteochondral tissue engineering. The goals of this work were to evaluate the effects of dynamic compressive loading (2.5% applied strain, 1 Hz) on osteogenesis in the stiff layer and spatially map local mechanical responses (strain, stress, hydrostatic pressure, and fluid velocity). A bilayer hydrogel was fabricated from soft (24 kPa) and stiff (124 kPa) poly (ethylene glycol) hydrogels. With hMSCs embedded in the stiff layer, osteogenesis was delayed under loading evident by lower OSX and OPN expressions, alkaline phosphatase activity, and collagen content. At Day 28, mineral deposits were present throughout the stiff layer without loading but localized centrally and near the interface under loading. Local strains mapped by particle tracking showed substantial equivalent strain (~1.5%) transferring to the stiff layer. When hMSCs were cultured in stiff single‐layer hydrogels subjected to similar strains, mineralization was inhibited. Finite element analysis revealed that hydrostatic pressures ≥~600 Pa correlated to regions lacking mineralization in both hydrogels. Fluid velocities were low (~1–10 nm/s) in the hydrogels with no apparent correlation to mineralization. Mineralization was recovered by inhibiting ERK1/2, indicating cell‐mediated inhibition. These findings suggest that high strains (~1.5%) combined with higher hydrostatic pressures negatively impact osteogenesis, but in a manner that depends on the magnitude of each mechanical response. This work highlights the importance of local mechanical responses in mediating osteogenesis of hMSCs in bilayer hydrogels being studied for osteochondral tissue engineering.     

从BMSCs探讨“肾主骨生髓”理论指导下中医药治疗骨质疏松症的研究

摘要：骨髓间充质干细胞(bone marrow mesenchymal stem cells, BMSCs)是在一定条件下能够向成骨细胞分化的多能干细胞，其增殖分化与中医“肾主骨生髓”理论及骨质疏松症(osteoporosis, OP)关系密切，大量研究表明传统补肾中药诱导BMSCs增殖分化治疗OP疗效显著。本文以中医“肾主骨生髓”理论为指导，探讨“肾藏精-主骨生髓-BMSCs-OP”之间的科学内涵，并探讨“补肾生髓”理论指导下传统补肾中药通过诱导BMSCs成骨分化与OP的关系，结合补肾中药及复方诱导BMSCs治疗OP的现代医学研究，为进一步探索有效的中医药治疗方案及发挥中医药独特优势提供依据。     

Alterations of upper airway volume caused by Le Fort III osteodistraction in children

PurposeThe aim of the study was to assess changes in the upper respiratory tract and sleep quality in patients who were suffering from midfacial hypoplasia and treated with the movement of underdeveloped middle segment of the face with an Le Fort III osteotomy and distraction.MethodsIn this study patients aged 7–19, suffering from Crouzon syndrome, Apert syndrome, or other craniosynostosis were treated with Le Fort III osteotomy and midface distraction. Patients were subjected to radiological examination and polysomnography before and after the treatment. Typical anthropometric points were identified on lateral cephalograms, and were used to take linear and angular measurements. The surface and the volume of the upper respiratory tract were measured with the Dolphin Imaging software. Apnoea Hypopnea Index (AHI) was used to assess the sleep quality.ResultsIn all 18 patients the analysis showed statistically significant changes of the AHI and in the linear, angular and volumetric measurements. Mean change of the volume of the upper respiratory tract was 12,4 ± 11,3cm3(p = 0,0001) and of the surface was 615 ± 521 mm² (p = 0,0000000002). Mean improvement of AHI was 9 ± 6,2 (p = 0,00006). In three cases patients had tracheostomy prior to operation and none of them required tracheostomy after the operation.ConclusionsThe use of distraction osteogenesis of the middle segment of the face combined with Le Fort III osteotomy results in dilation of the upper respiratory tract at the nasopharyngeal level and at the soft palate level resulting in elimination of sleep and respiration disorders. Further studies with polysomnography are necessary, as well as observation of patients over time and monitoring of treatment stability.