Role of the P2X7 Receptor in the Osteogenesis of Heterotopic Ossification of the Achilles Tendon

Background Heterotopic ossification (HO) refers to a painful and complex disease. HO occurs in the setting of persistent systemic inflammation and appears in flare-ups during inflammation, following injury. In the recent research, the P2X7 receptor (P2X7R) is tightly involved in the osteogenesis of periodontal ligament stem cells under the inflammatory conditions. The ionotropic P2X7 receptor (P2X7R) is an ATP-gated ion channel expressed in the majority of stem cells. However, the function of P2X7R in the pathological formation of HO is unclear. Here, this paper hypothesizes that in the model of Achilles tendon ectopic ossification, P2X7R is overexpressed in tendon-derived stem cells and promote osteogenesis of tendon-derived stem cells under inflammatory conditions. Methods The tenotomy puncture and burn injury-induced HO model was constructed. The qPCR and immunofluorescence were used to detect the expression of P2X7R at the site of injured Achilles tendon where HO occurs. Achilles tendon stem cells (SCs) from control group and experimental group sources were cultivated separately under inflammatory conditions. The cells from the two groups were cultured for osteogenic analysis. In addition, a specific antagonist of P2X7R, BBG was used to detect whether reversed the above process. At last, BBG was used to intervene in animal models of heterotopic ossification. Results Under inflammatory conditions, P2X7R expression of the Achilles tendon and osteogenic capability of SCs is higher in heterotopic ossification group (HOG) than in other two groups. The P2X7R expression was positive correlated with the capacity of osteogenesis of SCs. BBG can inhibit osteogenic differentiation and subsequent bone formation in the P2X7R overexpress of SCs. BBG impeded the heterotopic bone formation in animal model. Conclusions P2X7R is one of the crucial mediators in the formation of the HO, blocking which may represent a potential therapeutic target for HO.

Over-expression of wild-type ACVR1 in fibrodysplasia ossificans progressiva mice rescues perinatal lethality and inhibits heterotopic ossification

Fibrodysplasia ossificans progressiva (FOP) is a devastating disease of progressive heterotopic bone formation for which effective treatments are currently unavailable. FOP is caused by dominant gain-of-function mutations in the receptor ACVR1 (also known as ALK2), which render the receptor inappropriately responsive to activin ligands. In previous studies, we developed a genetic mouse model of FOP that recapitulates most clinical aspects of the disease. In this model, genetic loss of the wild-type Acvr1 allele profoundly exacerbated heterotopic ossification, suggesting the hypothesis that the stoichiometry of wild-type and mutant receptors dictates disease severity. Here, we tested this model by producing FOP mice that conditionally over-express human wild-type ACVR1. Injury-induced heterotopic ossification (HO) was completely blocked in FOP mice when expression of both the mutant and wild-type receptor were targeted to Tie2-positive cells, which includes fibro/adipogenic progenitors (FAPs). Perinatal lethality of Acvr1R206H/+ mice was rescued by constitutive ACVR1 over-expression and these mice survived to adulthood at predicted Mendelian frequencies. Constitutive over-expression of ACVR1 also provided protection from spontaneous HO, and the incidence and severity of injury-induced HO in these mice was dramatically reduced. Analysis of pSMAD1/5/8 signaling both in cultured cells and in vivo indicates that ACVR1 over-expression functions cell-autonomously by reducing osteogenic signaling in response to activin A. Manipulating the stoichiometry of FOP-causing and wild-type ACVR1 receptors may provide the foundation for novel therapeutic strategies to treat this devastating disease.

The miR-4739/DLX3 Axis Modulates Bone Marrow-Derived Mesenchymal Stem Cell (BMSC) Osteogenesis Affecting Osteoporosis Progression

Osteoporosis is a complex multifactorial disorder linked to various risk factors and medical conditions. Bone marrow-derived mesenchymal stem cell (BMSC) dysfunction potentially plays a critical role in osteoporosis pathogenesis. Herein, the study identified that miR-4739 was upregulated in BMSC cultures harvested from osteoporotic subjects. BMSCs were isolated from normal and osteoporotic bone marrow tissues and identified for their osteogenic differentiation potential. In osteoporotic BMSCs, miR-4739 overexpression significantly inhibited cell viability, osteoblast differentiation, mineralized nodule formation, and heterotopic bone formation, whereas miR-4739 inhibition exerted opposite effects. Through direct binding, miR-4739 inhibited distal-less homeobox 3 (DLX3) expression. In osteoporotic BMSCs, DLX3 knockdown also inhibited BMSC viability and osteogenic differentiation. Moreover, DLX3 knockdown partially attenuated the effects of miR-4739 inhibition upon BMSCs. Altogether, the miR-4739/DLX3 axis modulates the capacity of BMSCs to differentiate into osteoblasts, which potentially plays a role in osteoporosis pathogenesis. The in vivo and clinical functions of the miR-4739/DLX3 axis require further investigation.

Comment to: The utility of ultrasound examination in cubital tunnel syndrome caused by heterotopic ossification

Ultrasound (US) could visualize the pathological anatomy of HO and the enlargement site and compression location of the nerve in the cubital tunnel [1]. We read with great interest the article of Jačisko et al[2]. In addition, we report rare US images of HO in direct contact with the swollen ulnar nerve in the cubital tunnel that was not detected by plain radiography. A 60-year-old female presented with a six-month history of elbow pain. Her pain was located at the medial side of the right elbow joint and accompanied by numbness of the fifth finger. She had a history of excessive manual labor due to her occupation as a gardener over the past few decades. The numbness began with the fifth finger initially and gradually extended toward the medial side of the elbow joint. US images showed hyperechoic masses causing acoustic shadowing, in direct contact with the ulnar nerve in the cubital tunnel. The HO seems to be related to compression of the ulnar nerve. The ulnar nerve was swollen (Figure 1-a, b). The maximal cross-sectional-area was 0.10 cm2. Plain elbow radiographs demonstrated osteophyte formation in the coronoid process of the ulna, the coronoid fossa of the humerus, and in the radial head (Figure 1-c). Radiographic imaging showed no heterotopic bone formation in the soft tissues surrounding the medial side of the right elbow. We performed US-guided perineural injection with a mixture of 1 cc of 10 mg triamcinolone and 3 cc of 0.2 % ropivacaine. Her pain and numbness gradually diminished with no adverse effects. Her pain reduced by 70% after two weeks, with pain improvement sustained for 6 months after the injection. Jačisko et al[2]have presented some diagnostic US imaging on neuropathy caused by HO located close to the ulnar nerve in the cubital tunnel. Especially, this case showed definite heterotopic bone formation in the soft tissue surrounding the medial side of the elbow on plain radiography. The classic sonographic patterns of HO were defined by the presence of central hypoechoic area surrounded by foci of calcification [3, 4]. The distortion of normal soft tissue and the formation of hypoechoic areas, with or without foci of calcification can also be shown as early signs[3, 4]. The use of US for HO is highly sensitive and provides an earlier diagnosis compared with other radiologic modalities [3-5]. It can be an effective treatment strategy and may improve the prognosis of neuropathy. We highlight that US evaluation can provide early diagnostic information about ulnar nerve morphology and various HO formations even if plane radiographs did not show heterotopic bone formation in the soft tissues surrounding the medial side of the elbow.

The Treatment Advantage of Complex Acetabular Fractures by the Pararectus Approach

Background: The surgical treatment of complex acetabular fractures is one of the most challenging procedures for orthopedic surgeons. The Pararectus approach, as a reasonable alternative to the existing surgical procedures, was performed for the treatment of complex acetabular fractures involving the anterior column. This study aimed to evaluate outcome using the Pararectus approach for acetabular fractures involving anterior columns. Methods: Thirty-seven with displaced complex acetabular fractures involving anterior columns were treated between July 2016 and October 2019 using the Pararectus approach. The functional outcomes (using the Merle d Aubigné and Postel scoring system, WOMAC and modified Harris scoring), the quality of surgical reduction (using the Matta criteria), and postoperative complications were assessed with about 26 months follow-up.Results: Thirty-seven patients (mean age 53 years, range: 30-71; 28 male) underwent surgery. Mean intraoperative blood loss was 840 ml (rang: 400-2000 ml) and mean operating time was 210 min (rang: 140-500 min). The modified Merle d Aubigné score was excellent and good in 27 cases (73%), fair in 6 cases (16%), and poor in 3 cases (12%). The mean score was 88.5 (range:77-96) for the modified Harris Hip scores, and 22 (range:7-35) for the WOMAC scores after operation. Postoperative functional outcomes were significantly improved compared with preoperative outcomes (P<0.0001). The quality of reduction was anatomical in 21 cases (57%), satisfactory in 9 cases (24%), and unsatisfactory in 7 cases (20%). At follow-up, four patients developed a DVT, and heterotopic bone formation was observed in one patient. The hip osteoarthritis was not observed.Conclusion: The Pararectus approach achieved good functional outcomes and anatomical reduction in the treatment of complex acetabular fractures involving anterior column with minimal access morbidity.

P068 Abstract tin soldiers Global FOP patient search

While looking for one, you may find another: Tin Soldiers and the search for undiagnosed individuals with Fibrodysplasia Ossificans Progressiva (FOP) Background FOP is an ultra-rare condition where heterozygous, gain-of-function missense mutations in the ACVR1 gene result in progressive heterotopic bone formation in ligaments, tendons and muscles and result in severe disability.1 FOP has an estimated incidence of 0.6–1.3 per million individuals 2,3 suggesting that currently there are ∼8000 patients living with FOP worldwide, however only about 900 patients are currently diagnosed worldwide The diagnosis is made clinically by identification of typical malformations of the great toes as well as inflammatory swellings (flare-ups) that result in progressive and episodic ossification of soft connective tissues, often triggered by trauma.4 Muscle biopsies, though contraindicated, are frequently performed mistakenly during the course of diagnosis, as FOP is not a well-known condition. There is an urgent need to identify individuals with FOP across the globe in order to avoid harmful biopsies and to provide a pathway to care for patients with FOP. Tin Soldiers is a global FOP patient search program utilizing multimedia campaigns aimed at educating and bringing attention to FOP, to find individuals across the globe and to connect them to pathways of care. The mission is to identify every person with FOP who is currently undiagnosed, as well as to deliver education and support to those living with a diagnosis, but not connected to support networks. Once found, all people living with FOP are connected to pathways to care. The aim is to describe the Tin Soldiers global FOP patient search program approach and report early results of the program. Methods Tin Soldiers creates multimedia campaigns to create awareness and to educate medical professionals, healthcare workers, general public and local communities on FOP. At the heart of the communication program is story-telling of people living with FOP, from a feature-length documentary to public service announcements, animated short films and an 8-part Global Master Series—all designed to bring attention to FOP in order to find patients and provide a pathway to diagnosis and care. Importantly diagnosis is not the end of the journey, it’s just the beginning. Results Since official operations commenced in March 2020, Tin Soldiers has trained 535 medical professionals; established an African Clinicians Council of 10 doctors with the intention of mentoring others across the continent; increased the number of African patients with a diagnosis from 25 patients in December 2020–32 in April 2021. Connected previously diagnosed (but not connected) patients to a robust support network and held the first African FOP Family Gathering with clinicians from both South Africa and Nigeria. On the journey, patients with other conditions have been discovered including Juvenile Idiopathic Arthritis (JIA), Progressive Osseus Heteroplasia (POH) and Multiple Osteochondromas (MO). These patients have been diagnosed and connected to both medical care and patient support. Another important outcome is the continued education of doctors globally with the uptake of the CME Master Series in Russia and planned rollouts in Algeria, Nigeria, Kenya, Namibia, Sweden (in partnership with the national patient organization) and Brazil (under the First Lady’s patronage). Conclusion Tin Soldiers offers an innovative model of patient identification, diagnosis, support and education at all levels of care, using the power of story-telling and multi-media marketing. Such a model could be considered for raising the profile of other musculoskeletal or rare conditions and connecting patients to a functioning pathway to care.

A case of osseous metaplasia in a gastric hyperplastic polyp: An unexpected finding in a common polyp

Introduction/Objective Foveolar hyperplastic polyp is a common gastric polyp characterized by foveolar hyperplasia with erosion, acute and chronic inflammation, granulation tissue formation, and smooth muscle strands extending from the muscularis mucosae. Although foveolar hyperplastic polyps may rarely contain foci of dysplasia or invasive carcinoma, osseous metaplasia/heterotopic bone formation in foveolar hyperplastic polyps of the stomach is extremely rare with a few case reports. Methods/Case Report A 63-year-old female with a history of hypertension, sick sinus syndrome, and Hashimoto’s thyroiditis was referred to our facility for evaluation of a mass in segment eight of the liver. The liver biopsy showed a moderately differentiated adenocarcinoma, most consistent with intrahepatic cholangiocarcinoma. A screening gastrointestinal endoscopy revealed a 7-mm sessile polyp in the antrum. The polyp was removed with a cold snare. No other abnormalities were identified in the stomach. Sections of the polyp showed fragments of antral-type gastric mucosa with foveolar hyperplasia, erosion, acute and chronic inflammation, and focal granulation tissue formation. In addition, multiple foci of woven bone formation without bone marrow surrounding dilated gastric foveolae were identified. No Helicobacter infection, intestinal metaplasia, dysplasia or malignancy was identified histologically. Osseous metaplasia/heterotopic bone formation is a well-known finding reported in various neoplastic and non- neoplastic conditions. However, osseous metaplasia in foveolar hyperplastic polyps of the stomach is extremely rare. There have been only four previous case reports published in English language. Our current case shows clinicopathologic features similar to those of the previous case reports including the findings of small-sized polyp found incidentally in middle-aged patients with no clinical history of hypercalcemia or any other abnormalities causing heterotopic bone formation. Results (if a Case Study enter NA) N/A Conclusion Although the pathogenesis of osseous metaplasia in a gastric hyperplastic polyp remains unknown, the finding of osseous metaplasia in a gastric hyperplastic polyp is very intriguing.

Heterotopic Ossification in Benign and Malignant Renal Neoplasms

Introduction/Objective Heterotopic bone formation in renal neoplasms is a rare phenomenon. Ossification with or without marrow elements has been reported in both benign and malignant renal tumors. Due to its rarity, the epidemiological and clinical features of this finding are not well-documented. Herein, we have examined heterotopic ossification in renal neoplasms and summarized the epidemiological and clinical features of this entity. Methods/Case Report A database search on PubMed, Scopus, and Google Scholar was performed using a combination of proper search terms. Full article texts of all search results were reviewed with reference lists screened for additional articles matching the search criteria. The demographic details of the patients, disease characteristics, treatment, and outcomes were all extracted from full text articles and were summarized in a pre-standardized form. The inclusion criteria were set as any epithelial renal neoplasm with histological evidence of heterotopic ossification. A case of clear cell renal cell carcinoma (CCRCC) with heterotopic ossification diagnosed in our institution is included in the study. Results (if a Case Study enter NA) A total of 30 cases were found of renal neoplasms with bone formation. The majority of patients were between the ages of 40 to 60. The male to female ratio was 1:1. The majority (19/30) were histologically diagnosed as CCRCC, the most common subtype of kidney tumor with a few cases diagnosed as chromophobe RCC (4/30), papillary RCC (3/30), and cystic nephroma (2/30). Of the neoplasms reported, tumor size varied from 3.0 cm to 28.8 cm. Conclusion Heterotopic ossification of renal neoplasms often presents a diagnostic challenge to the radiologist as other benign conditions such as extramedullary hematopoiesis can be in the differential. The rarity of this phenomenon renders pre-surgical diagnosis difficult. Our study documents this phenomenon to be seen in a variety of renal neoplasms and underscores the necessity to be aware of this rare entity.

Low-grade fibromyxoid sarcoma with heterotopic bone formation: case report and review of the literature

Introduction/Objective Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon soft tissue malignancy with deceptively bland histologic appearance, and a tendency for late recurrence and metastasis. Cases with significant heterotopic ossification are rare. This presentation aims to characterize the features of LGFMSs showing heterotopic ossification reported in the literature, and further review the morphologic spectrum of this malignant neoplasm. Methods/Case Report We report the case of a 42-year-old male presenting with a 20-year history of a painless tumor in his left upper thigh. Computed tomography images showed coarse punctate peripheral calcifications, and the mass was resected. The tumor cells were immunohistochemically positive for MUC4, and positive for FUS (16p11.2) gene rearrangement by fluorescence in situ hybridization. Lamellar and woven bone with admixed adipose tissue was seen. Immunohistochemistry also showed focal weak to moderate staining for TLE-1. An English literature search using the terms “Evans tumor”, “low-grade fibromyxoid sarcoma”, “ossification”, “osseous metaplasia”, “bone metaplasia” and “bone formation” was performed. Nine cases were identified. The majority of subjects were males, with a mean age of 38 years (range of 12-61 years). The duration of symptoms before diagnosis ranged from a few months to 10 years. The tumor size ranged from 2.5 and to more than 12 cm. In a minority of subjects, calcifications were identified on imaging studies. Histologically, bone metaplasia was mainly seen at the periphery of the tumor. The majority of cases had a chromosomal translocation (FUS-CREB3L2 in 5 cases and EWSR1-CREB3L1 in one). Results (if a Case Study enter NA) NA Conclusion LGFMS is a tumor that can occur in a wide range of anatomical sites, and should be included in the differential diagnosis of any spindle cell neoplasm with hypocellular areas and bland cytology. Pathologists and clinicians should be aware of the rare possibility of heterotopic ossification in this tumor type, which can be radiologically detected as calcification and then confirmed histopathologically.