Ossification Process Research Articles

Novel Algorithm for Surgical Management of Cervical Ossification of Posterior Longitudinal Ligament: A Retrospective Cohort Study With 2-Year Follow-Up.

With the development of new technologies, the surgical algorithm for ossification of posterior longitudinal ligament (OPLL) in the cervical spine also needs to be updated. The aim of this study is to elucidate a new surgical classification algorithm to guide the choice of surgical approaches for cervical OPLL based on its location and extent. In this algorithm, anterior controllable antedisplacement and fusion (ACAF) will be used as a new surgical option. This is a single-centered, retrospective, cohort study utilizing a novel algorithm based on the following three criteria: (1) the positional relationship between ossification and uncinate process (UP), (2) the K-line, and (3) the ossification segment for surgical decision-making. Patients diagnosed with cervical OPLL who received surgical intervention guided by the algorithm were included. Patient demographics, Japanese Orthopedic Association (JOA) scores, surgical time, imaging data before and 2 years after surgery, and the occurrence of complications were extracted from the database. Paired t-test was used for intragroup comparison, and one-way ANOVA test was used for the intergroup analyses. Based on this novel algorithm, 15 patients with Type I, 8 patients with Type II a, 2 patients with Type II b1, 5 patients with Type II b2 were included. The decision-making for the surgical techniques used in each patient followed the recommendation of the novel algorithm. The postoperative JOA scores of all types of patients improved significantly (p < 0.05), and the invasion rates of vertebral canal had also been significantly reduced (p < 0.05). In terms of restoring cervical curvature, patients with Type I (receiving ACAF) and Type II b2 (receiving laminectomy with instrumented fusion) benefited more from surgery (p < 0.05). A new algorithm guiding the choice of surgical approach for cervical OPLL was validated in a series of 30 patients. Through this analysis, we obtained on their clinical outcomes and complications. ACAF surgery is an ideal choice for Type I patients, with ossification located between UPs, while for patients with ossification exceeding UPs, it is better to perform anterior cervical corpectomy and fusion or posterior surgery.

Radiological study of the ossification process of medial clavicular epiphysis: The influence of sex and laterality

Radiological study of the ossification process of medial clavicular epiphysis: The influence of sex and laterality

Fracture morphology and ossification process of the keel bone in modern laying hens based on radiographic imaging.

Keel bone fractures (KBF) are one of the most important welfare problems in commercial laying hens. Despite extensive research on the matter, its etiology remains unclear. Studying fracture characteristics in radiographic images can aid in the understanding of the disorder. The aim of the current study was to provide detailed description of fracture characteristics and explore ossification in the keel bone. In this descriptive study, repeated cross-sectional sampling was performed in one commercial laying hen flock. The flock was visited at 11 time points from 17-57 weeks of age (WOA), radiographing 30 laying hens at each visit resulting in altogether 330 unique radiographs. Fracture characteristics and the keel bone's level of ossification were assessed in each radiograph. In total, 344 fractures were recorded, of which 71.5% were complete and 28.5% were incomplete. Of the complete fractures, 82.9% were recorded as transverse, and 15.9% as oblique. One comminuted and two butterfly fractures were recorded. The caudal third of the keel was the most common area for fractures. Fracture characteristics differed between the different regions of the keel bone; all incomplete fractures in the cranial third appeared on the ventral surface of the keel, whilst the majority of incomplete fractures on the caudal third appeared on the dorsal surface. This indicates that the underlying etiology might differ between the cranial and caudal part. Folding fractures were observed in 18.6% of all the fractures, and occurred in both cranial-, and caudal third of the keel, indicating possible underlying disorders of calcium metabolism. All hens at 32 WOA and older had a fully ossified keel, based on radiographic evaluation. Displacement and soft tissue swelling are common characteristics in fractures of traumatic origin. We found a high frequency of simple fractures, without these characteristics, indicating that non-traumatic causes may be of higher importance than conventional beliefs.

Comparison of Vicious Effect of Oral Pantoprazole and Famotidine on New Bone Formation in Patients With Lumbar Spine Fusion Surgery: A Randomized Control Trial

Background and Aim: Due to the increasing use of proton pump inhibitors (PPIs) and their side effects for bone repair and the high percentage of therapy failure in lumbar fusion surgery, especially in various animal studies, the goal of this study was to appraise the consequence of pantoprazole and famotidine on new bone formation in patients experiencing spinal fusion surgery. Methods and Materials/Patients: In this double-blind clinical trial, eighty patients participated based on the inclusion and exclusion criteria, of whom 40 cases received pantoprazole (group P) and 40 received famotidine (group F) for eight weeks. They were followed up for three, six, and twelve months after surgery for cage subsidence, screw loosening, and visual analogue scale (VAS), Oswestry disability index (ODI), Brantigan, Steffee, Fraser (BSF), and Lenke classification for grading their bone formation. A P&lt;0.05 was considered significant. Results: The rate of fusion based on the Lenke score was lower in the group receiving pantoprazole six and 12 months after the surgery compared to group F (the frequency of Lenke grades C and D were 35% and 25% compared to the famotidine group 12.5% and 12.5%, respectively; P=0.042). The VAS Mean±SD score in group F was lower than group P after 12 months (2.48±1.06 and 1.83±0.55, respectively; P=0.008). There was no pharmacologically significant association between subsidence (P=0.43), loosening (P=0.13), ODI (P=0.31), and BSF (P=0.77) 3, 6 and 12 months post-operation. Conclusion: Affording to the preliminary conclusions of this study, the use of pump inhibitors, such as pantoprazole is more destructive for the ossification process in candidates for spinal fusion requiring the chronic use of drugs for controlling their gastric acid secretion, and H2-blocking drugs, such as famotidine are preferable in this situation after further investigations.

MODELING OSTEOCYTE UNDER SHOCK-WAVE THERAPEUTIC LOADING

Dental implants have substantial significance in modern dentistry, but their osseointegration stage remains the most crucial and time-consuming step for compensating for a lost tooth. One promising approach to improve osseointegration rates is the use of extracorporeal shock wave therapy, which has shown efficacy in treating fractures, bone defects, and bone tissue regeneration in surgical and arthroplasty procedures. To comprehend the potential of shock wave therapy in accelerating implant osseointegration, it is crucial to investigate the influence of mechanical loading on ossification processes of varying scales objectively. This study aims to study numerically the effects of low-energy shock wave therapy at different intensities on the mechanical response of a single osteocyte, the principal bone cell that corresponds to microscale of bone tissue. The investigation employs the method of movable cellular automata for modeling. The computer simulation results and analysis based on mechanobiological principles indicate that low-intensity shock wave loading creates conditions for intramembranous ossification, whereas high-intensity shock wave exposure creates conditions for endochondral ossification.

Resources for innovative learning of anatomy and foot ossification: Graphic design and virtual reality.

This study addresses the ossification process of the foot, a topic of great relevance within podiatry courses. Understanding the chronology of foot bone formation is essential for evaluating pathological processes and establishing appropriate therapeutic actions to improve patient quality of life. The main objectives of this work are to understand the ossification process of the foot bones and to propose an appropriate didactic methodology for effective learning of this process. The individual ossification sequences of the foot bones were established and virtually recreated to make these processes more didactic and usable as teaching aids. The literature search was conducted using the PRISMA statement, focusing on terms, such as "bone ossification," "foot," and "bone development," and included relevant studies from medical databases. Updating the ossification ages and providing previously unavailable visual teaching material offers a useful tool for improving the teaching of this subject. It was found that, in general, the tarsal bones show significant differences in ossification ages between sexes, with later and slower ossification in males. These differences are statistically analyzed and presented in detailed comparative tables. The use of innovative teaching tools, such as virtual anatomical models, helps students to better understand the ossification process of foot bones. Implementing these tools in the podiatry curriculum not only facilitates knowledge acquisition but also enhances the quality of teaching and, consequently, the future clinical practice of students.

Enhancing Telemedicine Communication for Improved Outpatient Pediatric Trauma Care.

Pediatric traumatology is a complex field that requires a comprehensive understanding of physeal development, remodeling potential, and the ossification process in order to ensure appropriate patient treatment. The objective of this study was to assess the willingness of practicing physicians to participate in a telemedicine collaboration aimed at enhancing the exchange between the outpatient and inpatient sectors and promoting the digitalization of the pediatric sector. This is in response to the growing significance of digitalization in the medical field. A survey consisting of 15 items was sent to 800 practicing trauma surgeons, pediatric surgeons, and pediatricians within a 100 km radius of Hamburg, Germany. The survey included questions about the respondents' professional experience and telemedicine experience, as well as inquiries about possible telemedicine collaborations. The response rate was 19.3%. Less than half of the participants already used telemedicine in daily practice. In general, 75% of respondents expressed an interest in collaborating with the inpatient sector. The most common reasons for hospital referral were the need for surgery, inadequate treatment of children in practice and co-assessment. The majority were in favor of flexible communication, either via video telephony, imaging applications like or messaging applications. The study revealed a high level of interest in telemedicine collaboration. Information exchange should be tailored to individual needs, with practitioners requiring a versatile and personalized approach that includes imaging. Strict enforcement of data protection regulations is essential. Further research is needed to evaluate the effectiveness of telemedicine collaboration in the treatment of pediatric trauma in both hospital and outpatient settings.

A Osteocondrose e a Traumatologia do Desporto

Osteochondrosis is defined as a failure in the endochondral ossification process. There is no consensus on the etiology, with multiple factors involved. The initial events in the pathogenesis remain uncertain, but evidence points to ischemic necrosis of the ossification center, located in the bone epiphysis. Each osteochondrosis has a homonymous clinical diagnosis assigned based on location. The most affected areas include the hip (Legg-Calvé-Perthes disease), knee (Osgood-Schlatter disease, Sinding-Larsen-Johansson disease), foot (Sever’s disease), elbow (Panner’s disease) and spine (Scheuermann’s disease). The most common clinical manifestations are mechanical pain and functional limitation during or after physical activity. Many injury prevention strategies involve educating young people, coaches, family members and monitoring symptoms. Early diagnosis and a structured approach allow, in most cases, clinical resolution and avoid long-term sequelae. Osteochondrosis was first described by König in 1887 and, despite more than a century of studies, there are still many challenging questions to elucidate to better understand this pathology.

Effects of Hindlimb Suspension on the Development of Hip Bone Morphologies in Growing Rats

Abnormal hip bone morphologies are associated with various diseases of the hip joint. Weight bearing, especially during growth, may be important to achieve normal acetabulum development. This study aimed to investigate whether hip bone morphologies were affected by hindlimb suspension (HS) in 4 week-old rats. In HS groups, tail suspension was applied for 0, 2, 4, and 8 weeks. Age-matched rats were used as controls. The complex of hip bones with lumbar and sacral vertebrae were assessed based on morphological indexes using three-dimensional reconstructed images from X-ray computed tomography. Acetabular widths (measured from cranial to caudal) unchanged and depths became larger in both groups with age. Acetabular lengths (from the ventral side to the dorsal side) became larger in control groups but unchanged in HS groups with age. In HS groups, acetabular width, length, and depths were smaller than the control groups at 4 and/or 8 weeks. Acetabular versions became enlarged (rotated inwards) with age in both groups, although this was particularly pronounced in HS groups. Histologically, triradiate cartilage layers in the acetabulum were thinner with age and almost disappeared at 8 weeks in both groups. However, HS decreased Safranin O staining and prolonged the presence of hypertrophic chondrocyte indicating alterations in the chondral ossification processes. Iliac wing angles remained unchanged and anterior superior iliac crest (ASIC) distances increased with age in controls. In contrast, HS groups showed narrowed iliac wing angles with small ASIC distances. These results suggest that reduced mechanical loading during growth can interfere with hip joint formation.

Digital anatomical features of morphological development in C2–C7 neurocentral synchondrosis in children aged 1–6 years: a retrospective study of CT images

BackgroundWith the continuous improvement of diagnosis and treatment technology for cervical spine-related diseases in children at home and abroad, the demand for exploring the developmental anatomy and function of children's cervical spine of different ages is increasing. So the aim of this study was to investigate the changes of anatomical indicators in neurocentral synchondrosis (NCS) of C2–C7 with age and the developmental characteristics of different vertebrae in children aged 1–6 years old.MethodA retrospective collection of 160 cases of normal cervical spine CT images of children aged 1–6 years old in provincial tertiary hospitals, according to the age group of 1-year-old into 6 groups. The original data of continuously scanned cervical spine tomography images were imported into Mimics16.0 software, under the two-dimensional image window, selected the measurement tool under the Measurements toolbar to measure and statistically analyzed the anatomical indicators such as cross diameter, sagittal diameter, height, perimeter and area of NCS in the C2–C7 segment of the cervical spine on the coronal plane and cross-section.ResultsThere was no significant difference in the anatomical indexes of cervical spine NCS in children compared with the left and right sides of the same vertebrae (P > 0.05). The same cervical spine generally had differences between the age groups of 1–4 years old and 5–6 years old (P < 0.05).The transverse diameter and circumference gradually decreased with age; the sagittal diameter and height showed a slight increase trend; there was a maximum area at 2 years of age. In different cervical vertebrae of the same age group, the NCS values of C3, C4, and C5 varied greatly, which showed that the ossification process of cervical cartilage was faster than that at the upper and lower ends. There were obvious differences between C2 and the rest of the cervical vertebral segments’ NCS ossification process. C7 was also very different from the rest of the cervical vertebrae segments, presumably more similar to the thoracic spine.ConclusionsThe anatomical indexes of C2–C7 NCS in children have obvious developmental regularities at different ages, and there are also regularities between cervical segments.

Rare radiological manifestation of enchondromatosis in children: Columnar pattern: A retrospective cohort study.

The columnar cartilage pattern is characterized by parallel aligned cartilage tissue columns related to the physis without matrix calcification separated by the surrounding osseous tissue. Usually, it is seen in patients with multiple enchondromas. The objective of this study was to elucidate the clinical and radiological features of this rare radiological pattern in the physis, which remains unfamiliar to most physician. We retrospectively evaluated the clinical features and imaging findings of 15 patients (9 men and 6 women) who have a columnar pattern with varied spectrum of enchondromatosis. On X-ray and computed tomography (CT) examination, all these lesions were seen as vertical or oblique oriented tubular zones, which have relatively low radiologic density compared with normal bone. The lesions have similar signal characteristics relative to epiphyseal cartilage plates, on T1W and T2W magnetic resonance images. Columnar pattern was observed in different appearances from one single column in one physis to multiple columns in multiple physis. The mean follow-up was 62 months (range: 36-96 months). The mean age was 9.7 (range: 4-14) years at the initial admission. Eight patients had 3 or less affected physis. Five patients had only one affected physis. We defined these patients' group who had up to 3 affected physis as "limited enchondromatosis with columnar pattern (LE-CP)." We observed that most of the columnar cartilage was turning into the normal bone via endochondral ossification. Based on our observations, the columnar pattern is a rare manifestation of the enchondromas. Columnar pattern, along with the related physis, acts as a normal endochondral ossification process, and surgery is not necessary unless there is a risk of fracture or severe deformity. Further awareness of this unique subset of patients may improve our understanding of the disease and lead to better patient outcomes. We have modified non-hereditarily enchondromatosis into 2 categories: limited enchondromatosis with the columnar pattern and multiple enchondromatosis. We believe that LE-CM reflects a developmental anomaly of the physis rather than a true neoplasia, and it acts as a normal endochondral ossification process. Level IV (case series).

Experimental confirmation and bioinformatics reveal biomarkers of immune system infiltration and hypertrophy ligamentum flavum.

Hypertrophy ligamentum flavum is a prevalent chronic spinal condition that affects middle-aged and older adults. However, the molecular pathways behind this disease are not well comprehended. The objective of this work is to implement bioinformatics techniques in order to identify crucial biological markers and immune infiltration that are linked to hypertrophy ligamentum flavum. Further, the study aims to experimentally confirm the molecular mechanisms that underlie the hypertrophy ligamentum flavum. The corresponding gene expression profiles (GSE113212) were selected from a comprehensive gene expression database. The gene dataset for hypertrophy ligamentum flavum was acquired from GeneCards. A network of interactions between proteins was created, and an analysis of functional enrichment was conducted using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases. An study of hub genes was performed to evaluate the infiltration of immune cells in patient samples compared to tissues from the control group. Finally, samples of the ligamentum flavum were taken with the purpose of validating the expression of important genes in a clinical setting. Overall, 27 hub genes that were differently expressed were found through molecular biology. The hub genes were found to be enriched in immune response, chemokine-mediated signaling pathways, inflammation, ossification, and fibrosis processes, as demonstrated by GO and KEGG studies. The main signaling pathways involved include the TNF signaling pathway, cytokine-cytokine receptor interaction, and TGF-β signaling pathway. An examination of immunocell infiltration showed notable disparities in B cells (naïve and memory) and activated T cells (CD4 memory) between patients with hypertrophic ligamentum flavum and the control group of healthy individuals. The in vitro validation revealed markedly elevated levels of ossification and fibrosis-related components in the hypertrophy ligamentum flavum group, as compared to the normal group. The TGF-β signaling pathway, TNF signaling pathway, and related hub genes play crucial roles in the progression of ligamentum flavum hypertrophic. Our study may guide future research on fibrosis of the ligamentum flavum.

Prevalence and characteristics of osseous bridging between vertebral bodies in the cervical spine: A skeletal study.

Osseous bridging (OB) in three or more segments of motions (SOMs) of the mobile spine was initially defined as diffuse idiopathic skeletal hyperostosis (DISH), located particularly in the thoracic spine (T-spine). This pathological phenomenon is often characterized by calcification and ossification, which take place simultaneously or separately. The soft tissues, mainly ligaments and entheses, are calcified, with bone formation not originating from the anterior longitudinal ligament (ALL). DISH formation can involve osteophytes, which are created by the ossification process and can involve soft tissue such as the ALL. The ALL can also be calcified. Until recently, the prevalence of DISH in the general population was considered low (0%-5%) and rare in the cervical spine (C-spine). In a cross-sectional observational skeletal study, we investigated the prevalence and location of C-spine OB between vertebral bodies with fewer than three SOMs. We tested a large sample (n = 2779) of C-spines housed in the Cleveland Museum of Natural History (Ohio, USA). The human sources of the samples had died between the years 1912 and 1938 and represented both sexes and two different ethnic groups: Black Americans and White Americans. The process development can be seen on the ALLs as calcification, osteophytosis, and candle-shaped. Among all of the specimens, 139 (5%) were affected by OB, mostly in one SOM. Prevalence tended to be higher in women, White Americans, and the older age group. The levels most affected were C3-C4, followed by C2-C3 and subsequently, C5-C6. OB involving two consecutive SOMs was found only at C5-C7. We believe it is important to respond to the presence of a single SOM with a presumptive diagnosis of OB and to follow up, identify whether the diagnosis is correct, and take preventive action if possible. There is a need for updated diagnostic criteria and research approaches that reflect contemporary lifestyle factors and their impact on spine health.

Formation of the Mandibular Condylar Cartilage in Human Specimens Between 10 and 15 Weeks of Gestation

Background: The study examines some morphological and histological factors that may contribute to condylar cartilage (CC) formation. The specimens used were consecutive sections obtained from 20 human fetuses ranging in age from 10 to 15 weeks. The vascular canals (VC) emerge in the CC and initiate the process of intramembranous ossification. The mandibular condylar cartilage is crucial for the growth and function of the mandible, and it also contributes to the development of the Temporomandibular joint. Understanding the development of mandibular condylar cartilage throughout the early stages of gestation is essential for detecting congenital craniofacial deformities. Objectives: Examine the stages of MCC development in human samples from fetuses at 10-15 weeks of gestation. Study Design: A descriptive Cross-sectional Study. Place and Duration of Study: Department of Anatomy and Obstetric Nowshera Medical College from 15th Nov 2020 to 1st Jun 2021. The changes in the shape and size of the bones and the processes of bone formation should also be determined. Methods: The current study is descriptive, cross-sectional, and involves post-mortem human fetal specimens aged 10-15 weeks. The specimens were obtained from the Department of Obstetrics of QHAMC after miscarriages and intrauterine deaths. The absence of external and congenital malformations was verified. Light microscopic and histological assessment was done with the aid of H&amp;E-stained sections. Results : Twenty fetal specimens were used in the study, with an average gestation period of 12. 5 weeks (±1. 5 weeks). Histological analysis revealed gradual chondrocyte maturation and the beginning of the ossification process. At ten weeks, MCC was comprised of undifferentiated mesenchymal cells. At twelve weeks, it is possible to observe the differentiation of chondrocytes and early ossification. At 15 weeks, the ossification stages of the CRL were at a superior level with the hypertrophic chondrocytes and mineralized cartilage. The p-values for differences in developmental stages between the gestational ages were less than 0. Hence, the differences were statistically significant. Conclusion: The MCC in human specimens at 10–15 weeks' gestation undergoes considerable morphological transformation and commences the ossification process. Knowledge of these stages is essential in identifying and intervening in congenital craniofacial disorders. The authors recommend that future studies focus on investigating molecular processes that may contribute to the development of MCC. Keywords: Mandibular condylar cartilage, Development, Gestation, Ossification

Effect of Platelet-Rich Fibrin Combined With Hyaluronic Acid on Bone Formation in Dental Implant Sockets: An In Vivo Study in Sheep.

The goal was to evaluate the effect of the combined growth factor of hyaluronic acid (HA) and advanced platelet-rich fibrin (A-PRF)on acceleration and maturation of bone formation around titaniumdental implants in the bone-free space (jumping distance) of anover-preparation socket. Thirty-two titanium dental implants were placed in four sheepand distributed into one control group (A) and three experimental groups (B, C, and D) in two different time periods.Each sheep received eight implants. The eight implants in each sheep were distributed into four groups. The first period was one month after the initial placement, 16 implants were used in two sheep. The second period was three months after the initial placement; another 16 implants were used in the other two sheep.All implants were placed in over-prepared implant sockets, resulting in minimal primary stability. In Group A: the space between the dental implant and the bone of the inner wall of the socket was left without a growth substrate material. In Group B: we added HA between the dental implant and the bone of the inner wall of the socket. In Group C: we added A-PRF between the dental implant and the bone of the inner wall of the socket. In Group D: we added a combination of HA and A-PRF between the dental implant and the bone of the inner wall of the socket. Data was collected for each group at one month and three months at the same time. A high-resolution, desktop micro-CT system (Bruker Skyscan 1275, Kontich, Belgium) was used to scan the specimens. The NRecon software (ver. 1.6.10.4, SkyScan) and CTAn (SkyScan) were used for the visualization and quantitative measurement of the samples. One-way analysis of variance (ANOVA) was used to compare the means of the four study groups in the same period. A post hoc test was used after ANOVA to compare the means of two samples at the same time. A p-value of ≤ 0.05 was considered statistically significant. After one month and three months of using combined HA and A-PRF on Group D, significant acceleration was observed in bone formation in all tests around dental implants compared with other groups, while no significant acceleration was observed when they were used separately; all three study groups showed significant results when compared with thecontrol group. Our data showed that using a combination of HA and A-PRF had a significanteffect on the acceleration of the bone formation and ossification process when added to bone-free space (jumping distance) around implants while leaving space without any growth substrates might delay the boneossification process.

Effectiveness of 3D visualization technologies in planning and performing reconstructive plastic surgeries in patients with elbow contractures caused by ossification

Background. Open reconstructive plastic surgeries are the most radical method of treating patients with elbow contractures caused by ossification. However, these surgeries pose a serious problem due to the large number of unsatisfactory results. The aim of the study is a comparative assessment of the effectiveness between standard techniques and 3D visualization technologies in the surgical treatment of patients with elbow contractures caused by ossification. Methods. Using random number generation, all patients (n = 71) were randomized into two groups. The first group included 34 patients with elbow contractures caused by ossification that underwent surgical intervention using 3D technologies to assess the ossification process. The second group enrolled 37 patients with a similar nosology that underwent standard examination and surgical treatment. The results were evaluated intraoperatively and 180 days after the surgery. The data were obtained from primary medical records and further survey. Results. The application of new planning technology and tactics for onstructive plastic surgeries made it possible to reduce the surgery time by 1.2 times (p0.05), reduce blood loss by 1.3 times (p0.05) and increase the relative number of patients with sufficient movement volume by 10.6% (p0.05). The assessment of various performance parameters (range of motion, pain syndrome, quality of life etc.) showed that after 6 months in the main group, the relative number of patients with problems related to the operated joint was significantly lower than in the control group: 20.5% vs 84.7% (p0.05). Conclusions. The data obtained indicate that the use of the new technique for planning and performing reconstructive plastic surgery in patients with elbow contractures caused by ossification contributes to a less invasive intervention and achievement of better intraoperative and medium-term treatment results.

Biomimetic Hydrogels as the Inductive Endochondral Ossification Template for Promoting Bone Regeneration.

Repairing critical size bone defects (CSBD) is a major clinical challenge and requires effective intervention by biomaterial scaffolds. Inspired by the fact that the cartilaginous template-based endochondral ossification (ECO) process is crucial to bone healing and development, developing biomimetic biomaterials to promote ECO is recognized as a promising approach for repairing CSBD. With the unique highly hydrated 3D polymeric network, hydrogels can be designed to closely emulate the physiochemical properties of cartilage matrix to facilitate ECO. In this review, the various preparation methods of hydrogels possessing the specific physiochemical properties required for promoting ECO are introduced. The materiobiological impacts of the physicochemical properties of hydrogels, such as mechanical properties, topographical structures and chemical compositions on ECO, and the associated molecular mechanisms related to the BMP, Wnt, TGF-β, HIF-1α, FGF, and RhoA signaling pathways are further summarized. This review provides a detailed coverage on the materiobiological insights required for the design and preparation of hydrogel-based biomaterials to facilitate bone regeneration.

Long-term haplodeficency of DSPP causes temporomandibular joint osteoarthritis in mice

BackgroundExtracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular condylar cartilage ECM protein, and its deletion impacted cell proliferation and other extracellular matrix alterations of postnatal condylar cartilage. However, it remains unclear if long-term loss of function of DSPP leads to TMJ OA. The study aimed to test the hypothesis that long-term haploinsufficiency of DSPP causes TMJ OA.Materials and methodsTo determine whether Dspp+/– mice exhibit TMJ OA but no severe tooth defects, mandibles of wild-type (WT), Dspp+/–, and Dspp homozygous (Dspp−/−) mice were analyzed by Micro-computed tomography (micro-CT). To characterize the progression and possible mechanisms of osteoarthritic degeneration over time in Dspp+/– mice over time, condyles of Dspp+/– and WT mice were analyzed radiologically, histologically, and immunohistochemically.ResultsMicro-CT and histomorphometric analyses revealed that Dspp+/– and Dspp−/− mice had significantly lower subchondral bone mass, bone volume fraction, bone mineral density, and trabecular thickness compared to WT mice at 12 months. Interestingly, in contrast to Dspp−/− mice which exhibited tooth loss, Dspp+/– mice had minor tooth defects. RNA sequencing data showed that haplodeficency of DSPP affects the biological process of ossification and osteoclast differentiation. Additionally, histological analysis showed that Dspp+/– mice had condylar cartilage fissures, reduced cartilage thickness, decreased articular cell numbers and severe subchondral bone cavities, and with signs that were exaggerated with age. Radiographic data showed an increase in subchondral osteoporosis up to 18 months and osteophyte formation at 21 months. Moreover, Dspp+/– mice showed increased distribution of osteoclasts in the subchondral bone and increased expression of MMP2, IL-6, FN-1, and TLR4 in the mandibular condylar cartilage.ConclusionsDspp+/– mice exhibit TMJ OA in a time-dependent manner, with lesions in the mandibular condyle attributed to hypomineralization of subchondral bone and breakdown of the mandibular condylar cartilage, accompanied by upregulation of inflammatory markers.

USING FOETAL SKELETOGENESIS TO EVALUATE AND IMPROVE IN VITRO CHONDROGENESIS PROTOCOLS

The reliable production of _in vitro_ chondrocytes that faithfully recapitulate _in vivo_ development would be of great benefit for orthopaedic disease modelling and regenerative therapy(1,2). Current efforts are limited by off-target differentiation, resulting in a heterogeneous product, and by the lack of comparison to human tissue, which precludes detailed evaluation of _in vitro_ cells(3,4).We performed single-cell RNA-sequencing of long bones dissected from first-trimester fetal limbs to form a detailed ‘atlas’ of endochondral ossification. Through 100-gene in-situ sequencing, we placed each sequenced cell type into its anatomical context to spatially resolve the process of endochondral ossification. We then used this atlas to perform deconvolution on a series of previously published bulk transcriptomes generated from _in vitro_ chondrogenesis protocols to evaluate their ability to accurately produce chondrocytes.We then applied single-nuclear RNA-sequencing to cells from the best performing protocol collected at multiple time points to allow direct comparison between the differentiation of _in vitro_ and _in vivo_ cells.We captured 275,000 single fetal cells, profiling the development of chondrocytes from multipotent mesenchymal progenitors to hypertrophic cells at full transcriptomic breadth. Using this atlas as the ground truth for evaluating _in vitro_ cells, we found substantial variability in cell states produced by each protocol, with many showing little similarity to _in vivo_ cells, and all exhibiting off-target differentiation.Trajectory alignment between _in vivo_ and _in vitro_ single-cell data revealed key differences in gene expression dynamics between _in vitro_ and _in vivo cells,_ with several osteoblastic transcription factors erroneously unregulated _in vitro,_ including _FOXO1._Using this information, we inhibited _FOXO1_ in culture to successfully increase chondrocyte yield _in vitro._This study presents a new framework for evaluating tissue engineering protocols, using single-cell data to drive improvement and bring the prospect of true engineered cartilage closer to reality.

Single Cell Profiling Reveals Unique Contributions of Senescent Macrophages across Musculoskeletal Tissues in Posttraumatic Osteoarthritis

Injury to the acute cruciate ligament (ACL) disrupts musculoskeletal tissue architecture and function, leading to atrophy and weakness associated with the development of posttraumatic osteoarthritis (PTOA). The objective of this study was to profile senescent cell burden across skeletal muscle and knee joint capsule compartments and to ascertain the effectiveness of senolytic treatment in mitigation of PTOA. Given the unique features of these tissues, we hypothesized that composition and physiological consequence of senescent cell burden would differ among muscle and joint capsule, and senolytic treatment would prevent cartilage degradation and improve muscle function. We employed a surgical ACL transection model (ACLT) and performed scRNAseq analysis on the quadriceps and joint capsule 14-days post-injury and discerned senescent status by SPiDER-βGal. We also examined the influence of senescent cells on neighboring populations in vitro. We investigated whether senolytic treatment (dasatinib and quercetin; D+Q) improves muscle and joint health 28-d post-injury. scRNAseq revealed that macrophages (MΦ) accounted for 83% of senescent cells in the quadriceps and 48% in the joint capsule. Senescent MΦ exhibited an alternatively activated phenotype (M2) . Gene ontology enrichment analysis in the quadriceps showed downregulation of positive regulation of muscle cell differentiation, and upregulation of secretory granule lumen; in the joint capsule, it revealed upregulation of glycosaminoglycan catabolic process and regulation of ossification. In vitro, we found that mesenchymal progenitors incubated with senescent MΦ conditioned media exhibited upregulation of senescence associated secretory phenotype (SASP) genes and extracellular matrix organization-related genes ( i.e.Col1a1 and Lox). We found upregulation of protein glycosylation and downregulation of chondroitin sulfate proteoglycan biosynthetic process pathways. PTOA mice exhibited significant reductions in quadriceps myofiber cross-sectional area, increased accumulation of M2-like Cd163+ MΦ, and increased fibrosis, which were blunted in D+Q-treated mice. D+Q-treated PTOA mice exhibited a trend of improved peak torque compared to vehicle-treated PTOA mice. Histochemical assessment of whole knee joints revealed compromised articular cartilage and moderate to severe PTOA in vehicle-treated mice, which was blunted in D+Q-treated mice. These findings reveal distinct transcriptional profiles of senescent macrophages isolated from unique musculoskeletal tissues, providing critical insight into the heterogeneity of senescent cell programming following traumatic injury. Further, we show that accumulation of senescent alternatively-activated MΦ likely contributes to musculoskeletal dysfunction and development of PTOA, and that senolytics may improve functional recovery. AR072061. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.