Interplay of Nkx3.2, Sox9 and Pax3 Regulates Chondrogenic Differentiation of Muscle Progenitor Cells

Muscle satellite cells make up a stem cell population that is capable of differentiating into myocytes and contributing to muscle regeneration upon injury. In this work we investigate the mechanism by which these muscle progenitor cells adopt an alternative cell fate, the cartilage fate. We show that chick muscle satellite cells that normally would undergo myogenesis can be converted to express cartilage matrix proteins in vitro when cultured in chondrogenic medium containing TGFß3 or BMP2. In the meantime, the myogenic program is repressed, suggesting that muscle satellite cells have undergone chondrogenic differentiation. Furthermore, ectopic expression of the myogenic factor Pax3 prevents chondrogenesis in these cells, while chondrogenic factors Nkx3.2 and Sox9 act downstream of TGFß or BMP2 to promote this cell fate transition. We found that Nkx3.2 and Sox9 repress the activity of the Pax3 promoter and that Nkx3.2 acts as a transcriptional repressor in this process. Importantly, a reverse function mutant of Nkx3.2 blocks the ability of Sox9 to both inhibit myogenesis and induce chondrogenesis, suggesting that Nkx3.2 is required for Sox9 to promote chondrogenic differentiation in satellite cells. Finally, we found that in an in vivo mouse model of fracture healing where muscle progenitor cells were lineage-traced, Nkx3.2 and Sox9 are significantly upregulated while Pax3 is significantly downregulated in the muscle progenitor cells that give rise to chondrocytes during fracture repair. Thus our in vitro and in vivo analyses suggest that the balance of Pax3, Nkx3.2 and Sox9 may act as a molecular switch during the chondrogenic differentiation of muscle progenitor cells, which may be important for fracture healing

18F-NaF PET/CT imaging of bone formation induced by bioactive glass S53P4 after mastoid obliteration

Purpose: Bioactive glass has been successfully used for surgical treatment of chronic infections in bone and bone cavities. Besides infection control, new bone formation is induced by the bioactive glass which is considered to have osteoconductive properties. Evaluation of postsurgical changes after bone graft surgery is generally performed with conventional radiographs or CT/MR imaging, but 18F-NaF PET/CT might be more suitable since it has a high and rapid bone uptake, accompanied by a fast blood clearance leading to a high bone to background ratio. Case: Obliteration with S53P4 bioactive glass of the mastoid and middle ear was performed in a patient suffering from chronic otitis media. Control of the chronic otitis media was achieved, and follow-up imaging after 3 years with 18F-NaF PET/CT showed increased uptake in the obliterated cavity indicating new bone formation. Conclusion: 18F-NaF PET/CT is able to detect new bone formation after obliteration of the mastoid with S53P4 bioactive glass

Efficacy of S53P4 Bioactive Glass for the Secondary Obliteration of Chronically Discharging Radical Cavities

Abstract Objective Present the results of the secondary obliteration of chronically discharging radical cavities using S53P4 bioactive glass (BAG). Study Design Retrospective cohort study. Setting Single‐center study. Methods A single‐center retrospective cohort study was conducted of all patients that underwent secondary obliteration of persistently draining radical cavities using S53P4 BAG between 2011 and 2022. Patients with middle ear cholesteatoma were excluded. The main outcome was postoperative otorrhea, as indicated by Merchant grading. Results In total, 97 patients were included. The median postoperative follow‐up time was 3.9 years (range 0.5‐10.4). Average time between the original canal wall down surgery and the secondary obliteration was 25.3 years (SD 11.7, range 2‐66). At the most recent follow‐up visit, a Merchant grade of 0 to 1 was observed in 95% of the cases. There were no cases of sensorineural hearing loss or facial palsy, one case developed a retro auricular skin defect and 1 patient developed CSF leakage. Minor complications were seen in 10 patients (10%). Ossicular chain reconstruction with a titanium prosthesis was performed in 42 cases, resulting in a median improvement of 11.2 dB in air conduction thresholds. In 9/42 cases (21%), closure of the postoperative air‐bone gap to ≤20 dB was achieved. Twenty‐five percent of cases could be discharged from out‐patient visits. Conclusion Revision of persistently draining radical cavities with BAG obliteration is feasible and results in a dry and safe ear in 95% of the patients, thereby enabling wearing of a conventional hearing aid. Out‐patient visits could be ceased in 25% of the cases

Efficacy of S53P4 Bioactive Glass for the Secondary Obliteration of Chronically Discharging Radical Cavities

Publication status: PublishedAbstractObjectivePresent the results of the secondary obliteration of chronically discharging radical cavities using S53P4 bioactive glass (BAG).Study DesignRetrospective cohort study.SettingSingle‐center study.MethodsA single‐center retrospective cohort study was conducted of all patients that underwent secondary obliteration of persistently draining radical cavities using S53P4 BAG between 2011 and 2022. Patients with middle ear cholesteatoma were excluded. The main outcome was postoperative otorrhea, as indicated by Merchant grading.ResultsIn total, 97 patients were included. The median postoperative follow‐up time was 3.9 years (range 0.5‐10.4). Average time between the original canal wall down surgery and the secondary obliteration was 25.3 years (SD 11.7, range 2‐66). At the most recent follow‐up visit, a Merchant grade of 0 to 1 was observed in 95% of the cases. There were no cases of sensorineural hearing loss or facial palsy, one case developed a retro auricular skin defect and 1 patient developed CSF leakage. Minor complications were seen in 10 patients (10%). Ossicular chain reconstruction with a titanium prosthesis was performed in 42 cases, resulting in a median improvement of 11.2 dB in air conduction thresholds. In 9/42 cases (21%), closure of the postoperative air‐bone gap to ≤20 dB was achieved. Twenty‐five percent of cases could be discharged from out‐patient visits.ConclusionRevision of persistently draining radical cavities with BAG obliteration is feasible and results in a dry and safe ear in 95% of the patients, thereby enabling wearing of a conventional hearing aid. Out‐patient visits could be ceased in 25% of the cases.</jats:sec

Mastoid Obliteration Using S53P4 Bioactive Glass in Cholesteatoma Surgery: A 10-Year Single-Center Experience in 173 Adult Patients with Long-Term Magnetic Resonance Imaging Controlled Follow-up

OBJECTIVE: To present the long-term outcomes of mastoid obliteration in cholesteatoma surgery using S53P4 bioactive glass (BAG) in an adult population. STUDY DESIGN: Retrospective cohort study. SETTING: Single-center study. PATIENTS: All 173 adult patients who underwent primary or revision surgery for cholesteatoma with mastoid obliteration using S53P4 BAG with at least 1 year of follow-up including nonecho planar diffusion-weighted magnetic resonance imaging (MRI) (non-EP DWI MRI) and/or second-look surgery to evaluate recidivism. Both canal wall up (CWU) and canal wall down (CWD) procedures were included. INTERVENTIONS: Patients underwent CWU or CWD mastoidectomy using S53P4 BAG. MAIN OUTCOME AND MEASURES: Cholesteatoma recidivism, postoperative complications, Merchant grade, hearing outcome. RESULTS: Cholesteatoma recidivism was assessed by MRI in 97% of all cases and second-look surgery look surgery in 3% of cases. After a mean follow-up period of 53 months, cholesteatoma recidivism was seen in 10% of the cases (n = 18). Using the Kaplan-Meier curve to extrapolate, a 5-year recidivism rate of 12% was estimated. Only minor complications occurred, all resolving spontaneously or after minor treatment. Merchant grade of 0 to 1 was achieved 95% of the patients, no persistently wet ears were observed. Closure of the air-bone gap within 20 dB was possible in 32%. CONCLUSION: In this long-term (up to 10 yr) follow-up study, we demonstrated the safety of S53P4 BAG. Minimal and only minor postoperative complications were observed. The effectiveness of BAG was indicated by the low rate of recidivism, even when using non-EP DWI MRI, a sensitive and specific noninvasive technique to detect cholesteatoma recidivism

Cholesteatoma surgery in the pediatric population: remaining challenges in the era of mastoid obliteration

Purpose: To present the first pediatric study on the safety and efficacy of mastoid obliteration using S53P4 bioactive glass (BAG) for cholesteatoma surgery. Methods: A single-center retrospective cohort study was conducted. Inclusion criteria were pediatric cases (≤ 18 years) and at least at least one year of follow-up including non-echo planar diffusion-weighted MRI to assess cholesteatoma recidivism. Both canal wall up (CWU) and canal wall down (CWD) procedures were evaluated. Results: A total of 61 cases (56 patients) were included. Most cases had an otologic history before the development of the cholesteatoma. CWU procedure was performed in 18 cases (30%) and CWD procedure in 43 cases (70%). The cholesteatoma recidivism rate was 33% after a mean follow-up period of 58 months. Kaplan–Meier curve estimated a 5-year recidivism rate of 40%. Few complications were seen that were all minor and resolved spontaneously or after local or systemic treatment. Control of the infection (merchant grade 0–1) was achieved in 98% of the cases. Closure of the air–bone gap within 20 dB was achieved in 22% of the cases with complete audiometric evaluation. Conclusion: In this MRI-controlled study, we show the safety and efficacy of S53P4 BAG for mastoid obliteration in a pediatric cholesteatoma cohort. Postoperative complications were both rare and minor, and a dry ear was achieved in almost all patients. Nevertheless, persistent hearing loss and the apparent high recidivism rate reflect the challenging nature of pediatric cholesteatoma

Radioimmunotherapy in patients with head and neck squamous cell carcinoma: Initial experience

Background. Despite improvements in locoregional treatment of stages III/IV squamous cell carcinoma of the head and neck (HNSCC), local and distant failure rates remain high. An effective adjuvant therapy is required for these patients. Among novel approaches is radioimmunotherapy, in which monoclonal antibodies (MAbs) are used for selective delivery of radiation to tumor cells. Methods. The suitability of 186Re-labeled chimeric MAb U36 (186Re-cMAb U36) for radioimmunotherapy was evaluated in a phase I study, with radiation dose escalating steps of 11, 27, and 41 mCi/m2. Tumor targeting was monitored with a gamma camera, and the maximum tolerated dose was established in 13 patients with recurrent or metastatic disease. Results. Administrations were well tolerated, and excellent targeting of tumor lesions was seen. Myelotoxicity was the only toxicity observed, resulting in dose-limiting toxicity in two patients treated with 41 mCi/m2. The MTD was established at 27 mCi/m2. A marked reduction in tumor size was observed in two patients, another showed stable disease for 6 months. Conclusions. Radioimmunotherapy with 186Re-cMAb U36 seems to be well tolerated, with bone marrow being the dose-limiting organ. The observation of antitumor effects is encouraging for further development of radioimmunotherapy for HNSCC

Safety, biodistribution, pharmacokinetics, and immunogenicity of 99mTc-labeled humanized monoclonal antibody BIWA 4 (bivatuzumab) in patients with squamous cell carcinoma of the head and neck

Previous studies have shown the potential of murine and chimeric anti-CD44v6 monoclonal antibodies (MAbs) for radioimmunotherapy (RIT) of head and neck squamous cell carcinoma (HNSCC). A limitation of these MAbs, however, appeared to be their immunogenicity. Therefore, humanized monoclonal antibody BIWA 4 (bivatuzumab), with an intermediate affinity for CD44v6, was recently selected. As a prelude to RIT, we evaluated the safety, tumor-targeting potential, pharmacokinetics, and immunogenicity of technetium-99m-labeled BIWA 4 in patients undergoing operations for primary HNSCC in this study. Ten patients were treated at BIWA 4 dose levels of 25 mg (n=3), 50 mg (n=4), and 100 mg (n=3). Patients received 2 mg of 750 MBq 99mTc-BIWA 4, together with 23-, 48-, and 98-mg unlabeled BIWA 4, respectively. Radioimmunoscintigraphy (RIS) was performed within 1 h and after 21 h, and patients underwent surgery at 48 h after injection. Biodistribution of 99mTc-BIWA 4 was evaluated by radioactivity measurements in blood, bone marrow, and in biopsies of a surgical specimen obtained 48 h after injection. BIWA 4 concentration in blood was assessed by ELISA and high performance liquid chromatography and related to soluble CD44v6 levels in serum samples. The development of human anti-human antibody (HAHA) responses was determined. Administration of 99mTc-BIWA 4 was well tolerated by all patients and no HAHA responses were observed. A mean t1/2 in plasma of 54.8±11.5 h, 76.1±21.8 h, and 68.5±21.2 h was found for the 25-, 50-, and 100-mg dose group, respectively. No complex formation of BIWA 4 with soluble CD44v6 in blood was observed. RIS showed targeting of primary tumors and lymph node metastases in 8 of 10 and 1 of 5 patients, respectively. The highest tumor uptake and tumor to nontumor ratios were observed for the 50-mg dose group. Tumor uptake was 12.9±5.9, 26.2±3.1, and 15.4±1.9% of the injected dose (ID)/kg for the 25-, 50-, and 100-mg dose group, respectively, while the tumor to bone marrow ratios for these groups were 1.7±0.5, 3.2±1.1, and 2.0±0.6, respectively. Conclusion: 99mTc-BIWA 4 can safely be administered to patients with HNSCC, with absence of detectable HAHA responses. The 50-mg dose level showed the highest tumor uptake and tumor to nontumor ratios. These findings support the use of BIWA 4 for RIT studies in patients with HNSCC