Efficacy of foam sclerotherapy with polidocanol for the management of oral venous malformations.

The present aimed to examine the effectiveness of polidocanol-based foam sclerotherapy for oral venous malformations (OVMs). The present study performed a retrospective analysis of patients with OVMs who underwent sclerotherapy using polidocanol. Patients achieving the complete resolution of OVM were categorized as having a complete response (CR), those with a reduction in size from the initial diagnosis were categorized as having a partial response (PR), those with no change in size as stable disease (SD), and those with an increase in size as progressive disease (PD). A total of 16 patients, comprising 4 males and 12 females, underwent treatment with polidocanol foam therapy, covering 22 affected areas. The treatment administered resulted in CR in 6 cases and PR in 10 cases, with no instances of SD or PD. Apart from localized injection site pain or swelling, there were no severe side-effects reported, such as circulatory dynamic changes or skin necrosis. On the whole, these findings underscore the effectiveness of foam sclerotherapy with polidocanol as a viable treatment for venous malformations in the oral and maxillofacial regions.

bmp-2 Gene-Transferred Skeletal Muscles with Needle-Type Electrodes as Efficient and Reliable Biomaterials for Bone Regeneration.

BACKGROUND: Bone morphogenetic protein-2 (bmp-2) has a high potential to induce bone tissue formation in skeletal muscles. We developed a bone induction system in skeletal muscles using the bmp-2 gene through in vivo electroporation. Natural bone tissues with skeletal muscles can be considered potential candidates for biomaterials. However, our previous system using plate-type electrodes did not achieve a 100% success rate in inducing bone tissues in skeletal muscles. In this study, we aimed to enhance the efficiency of bone tissue formation in skeletal muscles by using a non-viral bmp-2 gene expression plasmid vector (pCAGGS-bmp-2) and needle-type electrodes. METHODS: We injected the bmp-2 gene with pCAGGS-bmp-2 into the skeletal muscles of rats' legs and immediately placed needle-type electrodes there. Skeletal tissues were then observed on the 21st day after gene transfer using soft X-ray and histological analyses. RESULTS: The use of needle-type electrodes resulted in a 100% success rate in inducing bone tissues in skeletal muscles. In contrast, the plate-type electrodes only exhibited a 33% success rate. Thus, needle-type electrodes can be more efficient and reliable for transferring the bmp-2 gene to skeletal muscles, making them potential biomaterials for repairing bone defects.

Pseudoaneurysm of the superficial temporal artery after sagittal split ramus osteotomy: A case report.

Sagittal split ramus osteotomy (SSRO) is a widely performed orthognathic surgery; however, among the various reported complications of SSRO, pseudoaneurysms are rarely reported. Pseudoaneurysms are rare vascular lesions formed by damage to the arterial wall that can occur after trauma or postoperatively, causing uncontrolled bleeding. The present report describes a case of a pseudoaneurysm that occurred after SSRO in a 22-year-old female patient. Le Fort I osteotomy and bilateral SSRO were performed under general anesthesia to improve the gummy smile and mandibular asymmetry of the patient. While osteotomizing the medial side of the left SSRO, major bleeding occurred from the soft tissue of the posterior margin of the mandibular branch. Direct compression with gauze and a local hemostatic agent stopped the bleeding. Immediately after returning to the ward, bleeding was observed from the left wound site and marked swelling of the left buccal area occurred. Contrast-enhanced computed tomography revealed a pseudoaneurysm of the left superficial temporal artery (STA). Subsequently, arterial embolization for the pseudoaneurysm was performed. Overall, the present report describes a rare case of pseudoaneurysm of the STA as a postoperative complication of SSRO.

Methotrexate­related other iatrogenic immunodeficiency­associated lymphoproliferative disorder in the CNS and medication­related osteonecrosis of the jaw occurring simultaneously: A case report.

Methotrexate-related other iatrogenic immunodeficiency-associated lymphoproliferative disorder (MTX-OIIA-LPD) is prone to extranodal involvement but rarely involves the central nervous system (CNS). The present study reports a case of MTX-OIIA-LPD of the CNS discovered during medication-related osteonecrosis of the jaw (MRONJ) treatment in a 76-year-old woman with rheumatoid arthritis (RA). The chief complaint of the patient was bone exposure and pain in the right mandibular molar. The patient had been receiving MTX for RA and alendronate sodium hydrate for osteoporosis, followed by denosumab. Treatment was initiated based on a diagnosis of MRONJ. However, the patient experienced lightheadedness and floating dizziness afterwards. Examinations revealed scattered neoplastic lesions in the brain. The histopathological diagnosis was diffuse large B-cell lymphoma. A systemic search also revealed adrenal involvement. Since the patient was taking MTX, a diagnosis of MTX-OIIA-LPD was made and MTX was discontinued. Chemotherapeutic agents were administered since the central lesions became symptomatic. The MTX-OIIA-LPD lesions in the brain and adrenal glands completely resolved 8 months after onset. The physical condition of the patient improved, and the bone-exposed areas became epithelialized. Reports on MTX-LPD in the oral and maxillofacial region are few, which may delay its diagnosis. Therefore, biopsy of oral lesions in patients with MRONJ who are taking MTX and collaboration with related diagnostic departments, such as rheumatology and hematology, must be done to initiate the diagnosis and treatment of extraoral MTX-LPD.

Congenital factor XI deficiency with multiple tooth extractions (Case report).

Congenital factor XI deficiency (CFXI) is a rare blood disorder that occurs in one of every one million individuals. Given its rarity, there are very few reports of surgical procedures performed in the oral region CFXI patients. The present study reports the case of a 43-year-old man with CFXI who experienced multiple tooth extractions. It also conducted a review of the literature and treatment outline. We preoperatively administered fresh frozen plasma (FFP) before the tooth extraction and continued to transfuse FFP at the rate of 2 units per day from day 1 to 4 of admission. The extractions were divided into two parts, maxillary and mandibular and the teeth extracted on days 2 and 4 of admission. The patient was discharged on day 6 of admission because there was good progress and no postoperative bleeding. Therefore, it was possible to perform multiple tooth extractions without abnormal bleeding in the oral cavity; the chance of bleeding was reduced by administering FFP and increasing local hemostasis in CFXI patients.

A rare case of a branchial cyst with calcification: A case report.

Branchial cysts are relatively rare lesions with lymphoid tissue in the underlying epithelium of the cyst wall. The present study describes the case of a branchial cyst with keratinization and calcification that occurred in the right submandibular region, along with a review of the literature. A 49-year-old female patient presented with a complaint of swelling in the right submandibular region. Computed tomography revealed a well-defined, cystic lesion located anterior to the sternocleidomastoid muscle, outside the hyoid bone, and in front of the submandibular gland. The cystic cavity presented an opaque image suggestive of calcification. Magnetic resonance imaging showed high-intensity lesions on both T2-weighted and short-τ inversion recovery images on the anterior margin of the right sternocleidomastoid muscle, just below the platysma muscle, with a clear demarcation from the surrounding tissue, and posterior compression and flattening of the submandibular gland. Cystectomy was performed under general anesthesia, and histopathological examination confirmed the diagnosis of branchial cyst with keratinized and calcified substances. The patient recovered well and had no complications or recurrence at ~2-year follow-up. This case highlights the rare occurrence of a branchial cyst containing calcification in the cystic cavity and provides a literature review of the factors contributing to the calcification.

An experience of displaced third molar roots removed using computer-assisted navigation system.

The frequency of displacement of a third molar root is low and considered a rare incident. A computer-assisted navigation system is a surgical support system that allows the patient to confirm the surgical site in three dimensions during surgery has recently been introduced to oral and maxillofacial surgery. We used a computer-assisted navigation system to remove a displaced third molar root in the floor of the mouth without complications and report the outline of the procedure and the effectiveness of the computer-assisted navigation system safety. This was a 56-year-old male who underwent extraction of the mandibular right third molar at a referral clinic. At that time, the proximal root fracture remained in the extraction socket, and the distal root fracture displaced to floor of the mouth. The patient was referred to our hospital immediately after tooth extraction. We extracted the displaced third molar root fracture under general anesthesia using a computer-assisted navigation system to accurately locate the root fracture and performed minimally invasive extraction. The root extraction was performed 18 days after the initial tooth extraction. No lingual nerve exposure was observed during surgery. No sensory abnormalities in the lower lip or tongue were observed postoperatively. Computer-assisted navigation system is a useful surgical support system that enables oral and maxillofacial surgical procedures and prevents postoperative complications such as lingual nerve palsy safety.

Associations Among Tooth Loss, Periodontitis, and Carotid Intima-Media Thickness: the Nagahama Study.

AIMS: This study aimed to clarify the relationships among tooth loss, periodontal condition, and subclinical atherosclerosis from the aspect of intensity, extent, and duration of inflammation. METHODS: This cross-sectional study included 9,778 people from the Nagahama Study, a large-scale, general population-based study conducted in Japan. The number of teeth and periodontal status, including the attachment level (AL) and pocket depth (PD) of representative teeth from six regions, were evaluated by dentists. The maximum intima-media thickness (IMT) of the common carotid artery was used as an index of atherosclerosis. RESULTS: In the multivariate analysis adjusted for conventional risk factors, a large number of missing teeth (＜9 remaining teeth), which related to long-lasting inflammation indicative of the highest stage of periodontitis, was identified as an independent determinant of IMT in a general population (coefficient: 0.042; 95% confidence interval [CI]: 0.016 to 0.068). The presence of two or more regions with an AL ≥4 mm, which is indicative of the progressing, long-lasting stages of periodontal inflammation, was also independently associated with IMT (coefficient: 0.016; 95% CI: 0.004 to 0.028). On the contrary, PD, a measure of the early and reversible phases of periodontal inflammation, and loss of AL in the group without tooth loss were not significantly associated with IMT, because of the limited degree of accumulated periodontitis. CONCLUSION: The present results suggest that the association between periodontitis and atherosclerosis depends on the inflammation intensity, extent, and duration.

Circulatory C-type natriuretic peptide reduces mucopolysaccharidosis-associated craniofacial hypoplasia in vivo.

Skeletal alterations in the head and neck region, such as midfacial hypoplasia, foramen magnum stenosis and spinal canal stenosis, are commonly observed in patients with mucopolysaccharidosis (MPS). However, enzyme replacement therapy (ERT), one of the major treatment approaches for MPS, shows limited efficacy for skeletal conditions. In this study, we analysed the craniofacial morphology of mice with MPS type VII, and investigated the underlying mechanisms promoting jaw deformities in these animals. Furthermore, we investigated the effects of C-type natriuretic peptide (CNP), a potent endochondral ossification promoter, on growth impairment of the craniofacial region in MPS VII mice when administered alone or in combination with ERT. MPS VII mice exhibited midfacial hypoplasia caused by impaired endochondral ossification, and histological analysis revealed increased number of swelling cells in the resting zone of the spheno-occipital synchondrosis (SOS), an important growth centre for craniomaxillofacial skeletogenesis. We crossed MPS VII mice with transgenic mice in which CNP was expressed in the liver under the control of the human serum amyloid-P component promoter, resulting in elevated levels of circulatory CNP. The maxillofacial morphological abnormalities associated with MPS VII were ameliorated by CNP expression, and further prevented by a combination of CNP and ERT. Histological analysis showed that ERT decreased the swelling cell number, and CNP treatment increased the width of the proliferative and hypertrophic zones of the SOS. Furthermore, the foramen magnum and spinal stenoses observed in MPS VII mice were significantly alleviated by CNP and ERT combination. These results demonstrate the therapeutic potential of CNP, which can be used to enhance ERT outcome for MPS VII-associated head and neck abnormalities.

Nonexposed antiresorptive agent-related osteomyelitis of the jaw: a single-center cohort study.

INTRODUCTION: The nonexposed variant of antiresorptive agent-related osteonecrosis of the jaw (ARONJ) presents with nonspecific clinical findings. The diagnosis of nonexposed ARONJ poses a critical challenge, and there is little evidence regarding its treatment and outcomes. This study aimed to examine the clinical outcomes in patients with nonexposed antiresorptive agent-related osteomyelitis of the jaw (AROMJ). The terms ARONJ and AROMJ were used separately in this study. MATERIALS AND METHODS: We enrolled patients with nonexposed AROMJ (osteomyelitis of the jaw without bone exposure associated with antiresorptive agents) with partial reference to an existing position paper on ARONJ. The initiating event of osteomyelitis was limited to periodontitis. Based on the findings of bone scintigraphy, panoramic radiography, computed tomography, and histopathological examination, we also used the hierarchical diagnostic criteria (HDC) for osteomyelitis of the jaw. RESULTS: There were 58 confirmed cases of nonexposed AROMJ based on the HDC. All patients had sufficient clinical findings to be diagnosed with nonexposed AROMJ as osteomyelitis underwent extraction with bone debridement. The healing rate was 93.1% (54/58). Univariable analysis showed a strong association between the healing status and malignant disease, while multivariable analysis showed no strong association between them. CONCLUSIONS: The present study had a relatively large sample size of patients with nonexposed AROMJ. The primary disease in patients with nonexposed AROMJ may not have a strong association with the healed status of the lesion. Based on its high healing rate, extraction with bone debridement in confirmed nonexposed AROMJ may prevent progression.

Effect of C-type natriuretic peptide on craniofacial skeletogenesis in mice during the pubertal growth spurt.

OBJECTIVE: This study aimed to determine the effect of C-type natriuretic peptide (CNP) overexpression on craniofacial growth during the pubertal growth period in mice. DESIGN: Six-week-old C57BL/6 mice were injected with pLIVE-Empty vectors (Control mice) and pLIVE-NPPC vectors (CNP mice) using the hydrodynamic method. Morphological analyses were performed at the age of 12 weeks. RESULTS: Micro-computed tomography (µCT) images showed significant (p < 0.05) hyperplasia in the maxilla along the sagittal plane (CNP mice: 13.754 mm, Control mice: 13.215 mm). Further, the images revealed significant bone overgrowth in the sagittal direction in the sphenoid (CNP mice: 6.936 mm, Control mice: 6.411 mm) and occipital (CNP mice: 4.051 mm, Control mice: 3.784 mm) bones in the CNP mice compared with that in the Control mice. Compared with SAP-Nppc-Tg mice in previous studies, although there was no effect on nose length and nasal bone length, the effect was sufficient to improve craniofacial hypogrowth. Furthermore, CNP promoted sagittal cranial growth by increasing the thickness of the spheno-occipital synchondrosis in organ cultures and nasal septal cartilage in micromass cultures, which were derived from 6-week-old mice. CONCLUSIONS: We have previously shown that the elevated blood levels of CNP from the neonatal period affect midfacial skeletogenesis by promoting endochondral ossification using mice (SAP-Nppc-Tg mice). The overexpression of CNP, even in 6-weeks-old mice, promoted growth in the sagittal direction within the maxillary region. These findings indicate the therapeutic potential of CNP for the treatment of midfacial hypoplasia during the pubertal growth spurt.

C-type natriuretic peptide facilitates autonomic Ca2+ entry in growth plate chondrocytes for stimulating bone growth.

The growth plates are cartilage tissues found at both ends of developing bones, and vital proliferation and differentiation of growth plate chondrocytes are primarily responsible for bone growth. C-type natriuretic peptide (CNP) stimulates bone growth by activating natriuretic peptide receptor 2 (NPR2) which is equipped with guanylate cyclase on the cytoplasmic side, but its signaling pathway is unclear in growth plate chondrocytes. We previously reported that transient receptor potential melastatin-like 7 (TRPM7) channels mediate intermissive Ca2+ influx in growth plate chondrocytes, leading to activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) for promoting bone growth. In this report, we provide evidence from experiments using mutant mice, indicating a functional link between CNP and TRPM7 channels. Our pharmacological data suggest that CNP-evoked NPR2 activation elevates cellular cGMP content and stimulates big-conductance Ca2+-dependent K+ (BK) channels as a substrate for cGMP-dependent protein kinase (PKG). BK channel-induced hyperpolarization likely enhances the driving force of TRPM7-mediated Ca2+ entry and seems to accordingly activate CaMKII. Indeed, ex vivo organ culture analysis indicates that CNP-facilitated bone growth is abolished by chondrocyte-specific Trpm7 gene ablation. The defined CNP signaling pathway, the NPR2-PKG-BK channel-TRPM7 channel-CaMKII axis, likely pinpoints promising target proteins for developing new therapeutic treatments for divergent growth disorders.

Periodontal Tissue as a Biomaterial for Hard-Tissue Regeneration following bmp-2 Gene Transfer.

The application of periodontal tissue in regenerative medicine has gained increasing interest since it has a high potential to induce hard-tissue regeneration, and is easy to handle and graft to other areas of the oral cavity or tissues. Additionally, bone morphogenetic protein-2 (BMP-2) has a high potential to induce the differentiation of mesenchymal stem cells into osteogenic cells. We previously developed a system for a gene transfer to the periodontal tissues in animal models. In this study, we aimed to reveal the potential and efficiency of periodontal tissue as a biomaterial for hard-tissue regeneration following a bmp-2 gene transfer. A non-viral expression vector carrying bmp-2 was injected into the palate of the periodontal tissues of Wistar rats, followed by electroporation. The periodontal tissues were analyzed through bone morphometric analyses, including mineral apposition rate (MAR) determination and collagen micro-arrangement, which is a bone quality parameter, before and after a gene transfer. The MAR was significantly higher 3-6 d after the gene transfer than that before the gene transfer. Collagen orientation was normally maintained even after the bmp-2 gene transfer, suggesting that the bmp-2 gene transfer has no adverse effects on bone quality. Our results suggest that periodontal tissue electroporated with bmp-2 could be a novel biomaterial candidate for hard-tissue regeneration therapy.

Association Between Tooth Loss and Longitudinal Changes in B-Type Natriuretic Peptide Over 5 Years in Postmenopausal Women: The Nagahama Study.

There is disparity between the sexes in cardiovascular diseases including heart failure (HF). This study aimed to investigate the effect of periodontal disease (PD) on plasma B-type natriuretic peptide (BNP) concentration across sex, age, and menopausal status, as well as the interaction effect of PD and diabetes mellitus (DM) on BNP. This large-scale prospective cohort study enrolled 7539 individuals with no myocardial infarctions or angina pectoris at baseline from the general Japanese population. The association between baseline number of missing teeth (MT) and the longitudinal changes in BNP over 5 years (ΔBNP) was evaluated according to sex and menopausal status. Among 7539 participants, 3190 were postmenopausal women with a mean age ± standard deviation of 61.1 ± 7.6 at baseline. Multivariate analysis revealed a positive association between MT and ΔBNP among postmenopausal women even after adjusting for covariates, including traditional HF risk factors (coefficient, 0.210; 95% confidence interval [CI], 0.107 to 0.312; P < 0.001), but not in men aged > 50. Including an interaction term (MT × DM) in the multivariate model revealed a positive interaction between MT and DM in ΔBNP among postmenopausal women (coefficient for interaction, 1.365; 95% CI, 0.902 to 1.827; P for interaction < 0.001). In conclusion, our study showed a positive association between MT and ΔBNP, as well as a positive effect of the interactive association between MT and DM, among postmenopausal women. Our results suggest a sex difference of an adverse effect of PD on initial myocardial wall stress in the ventricles.

Foramen magnum stenosis and midface hypoplasia in C-type natriuretic peptide-deficient rats and restoration by the administration of human C-type natriuretic peptide with 53 amino acids.

C-type natriuretic peptide (CNP)-knockout (KO) rats exhibit impaired skeletal growth, with long bones shorter than those in wild-type (WT) rats. This study compared craniofacial morphology in the CNP-KO rat with that in the Spontaneous Dwarf Rat (SDR), a growth hormone (GH)-deficient model. The effects of subcutaneous administration of human CNP with 53 amino acids (CNP-53) from 5 weeks of age for 4 weeks on craniofacial morphology in CNP-KO rats were also investigated. Skulls of CNP-KO rats at 9 weeks of age were longitudinally shorter and the foramen magnum was smaller than WT rats. There were no differences in foramen magnum stenosis and midface hypoplasia between CNP-KO rats at 9 and 33 weeks of age. These morphological features were the same as those observed in CNP-KO mice and activated fibroblast growth factor receptor 3 achondroplasia-phenotype mice. In contrast, SDR did not exhibit foramen magnum stenosis and midface hypoplasia, despite shorter stature than in control rats. After administration of exogenous CNP-53, the longitudinal skull length and foramen magnum size in CNP-KO rats were significantly greater, and full or partial rescue was confirmed. The synchondrosis at the cranial base in CNP-KO rats is closed at 9 weeks, but not at 4 weeks of age. In contrast, synchondrosis closure in CNP-KO rats treated with CNP-53 was incomplete at 9 weeks of age. Administration of exogenous CNP-53 accelerated craniofacial skeletogenesis, leading to improvement in craniofacial morphology. As these findings in CNP-KO rats are similar to those in patients with achondroplasia, treatment with CNP-53 or a CNP analog may be able to restore craniofacial morphology and foramen magnum size as well as short stature.

Direct evidence for the age-dependent demise of GNAS-mutated cells in oral fibrous dysplasia.

OBJECTIVE: Fibrous dysplasia (FD) is a benign bone disease characterized by fibro-osseous lesions. FD is caused by somatic mutations in the gene, guanine nucleotide-binding protein, alpha stimulating activity polypeptide 1 (GNAS), which encodes the G protein subunit, Gsα. FD manifests early in life, but the growth of lesions usually ceases in adulthood. FD lesions often exhibit somatic mutation mosaicism. In this study, the relationship between lesion growth and mutation prevalence within a lesion was investigated. DESIGN: Lesions from five FD patients were characterized by radiographical, histological and immunohistochemical methods. To accurately calculate the prevalence of mutations within lesions, GNAS codon 201 in genomic DNA isolated from fresh surgical FD specimens was sequenced. RESULTS: Uniquely, a lesion in one 46-year-old patient was still growing, enabling simultaneous analysis of both stable-old and active-new FD lesions in the same patient. Immunohistochemical analysis indicated that a newer, proximal lesion was growing while an older, distal lesion was not. The mutation prevalence differed between these lesions; it was low in the old and high in the new lesion. Thus, the frequency of mutated cells had decreased in the older lesion. CONCLUSIONS: This is the first direct evidence for the age-dependent demise of mutated cells in FD, helping to explain why FD lesion growth generally ceases in adulthood.

Rats deficient C-type natriuretic peptide suffer from impaired skeletal growth without early death.

We have previously investigated the physiological role of C-type natriuretic peptide (CNP) on endochondral bone growth, mainly with mutant mouse models deficient in CNP, and reported that CNP is indispensable for physiological endochondral bone growth in mice. However, the survival rate of CNP knockout (KO) mice fell to as low as about 70% until 10 weeks after birth, and we could not sufficiently analyze the phenotype at the adult stage. Herein, we generated CNP KO rats by using zinc-finger nuclease-mediated genome editing technology. We established two lines of mutant rats completely deficient in CNP (CNP KO rats) that exhibited a phenotype identical to that observed in mice deficient in CNP, namely, a short stature with severely impaired endochondral bone growth. Histological analysis revealed that the width of the growth plate, especially that of the hypertrophic chondrocyte layer, was markedly lower and the proliferation of growth plate chondrocytes tended to be reduced in CNP KO rats. Notably, CNP KO rats did not have malocclusions and survived for over one year after birth. At 33 weeks of age, CNP KO rats persisted significantly shorter than wild-type rats, with closed growth plates of the femur in all samples, which were not observed in wild-type rats. Histologically, CNP deficiency affected only bones among all body tissues studied. Thus, CNP KO rats survive over one year, and exhibit a deficit in endochondral bone growth and growth retardation throughout life.

Maxillary Hypoplasia With Congenital Oligodontia Treated by Maxillary Distraction Osteogenesis.

It is known that congenitally missing teeth can often cause differences in craniofacial morphology; however, there are few reported cases of orthognathic surgical treatment for these patients. Herein, the authors report a rare case of maxillary hypoplasia with congenital oligodontia treated by maxillary distraction osteogenesis with internal device. A 17-year-old male presenting with multiple tooth agenesis and maxillary recession was referred to our hospital for orthognathic surgical treatment. Preoperative simulation surgery was performed using Full-Color 3-dimensional salt model. After surgery, improvement in maxillary recession and occlusal stability was observed. This report demonstrates the advantages of the method used herein, which includes reduction in operating time with increase in the safety of the procedure.

Circulating osteocrin stimulates bone growth by limiting C-type natriuretic peptide clearance.

Although peptides are safe and useful as therapeutics, they are often easily degraded or metabolized. Dampening the clearance system for peptide ligands is a promising strategy for increasing the efficacy of peptide therapies. Natriuretic peptide receptor B (NPR-B) and its naturally occurring ligand, C-type natriuretic peptide (CNP), are potent stimulators of endochondral bone growth, and activating the CNP/NPR-B system is expected to be a powerful strategy for treating impaired skeletal growth. CNP is cleared by natriuretic peptide clearance receptor (NPR-C); therefore, we investigated the effect of reducing the rate of CNP clearance on skeletal growth by limiting the interaction between CNP and NPR-C. Specifically, we generated transgenic mice with increased circulating levels of osteocrin (OSTN) protein, a natural NPR-C ligand without natriuretic activity, and observed a dose-dependent skeletal overgrowth phenotype in these animals. Skeletal overgrowth in OSTN-transgenic mice was diminished in either CNP- or NPR-C-depleted backgrounds, confirming that CNP and NPR-C are indispensable for the bone growth-stimulating effect of OSTN. Interestingly, double-transgenic mice of CNP and OSTN had even higher levels of circulating CNP and additional increases in bone length, as compared with mice with elevated CNP alone. Together, these results support OSTN administration as an adjuvant agent for CNP therapy and provide a potential therapeutic approach for diseases with impaired skeletal growth.

Circulatory CNP Rescues Craniofacial Hypoplasia in Achondroplasia.

Achondroplasia is the most common genetic form of human dwarfism, characterized by midfacial hypoplasia resulting in occlusal abnormality and foramen magnum stenosis, leading to serious neurologic complications and hydrocephalus. Currently, surgery is the only way to manage jaw deformity, neurologic complications, and hydrocephalus in patients with achondroplasia. We previously showed that C-type natriuretic peptide (CNP) is a potent stimulator of endochondral bone growth of long bones and vertebrae and is also a potent stimulator in the craniofacial region, which is crucial for midfacial skeletogenesis. In this study, we analyzed craniofacial morphology in a mouse model of achondroplasia, in which fibroblast growth factor receptor 3 (FGFR3) is specifically activated in cartilage ( Fgfr3ach mice), and investigated the mechanisms of jaw deformities caused by this mutation. Furthermore, we analyzed the effect of CNP on the maxillofacial area in these animals. Fgfr3ach mice exhibited midfacial hypoplasia, especially in the sagittal direction, caused by impaired endochondral ossification in craniofacial cartilage and by premature closure of the spheno-occipital synchondrosis, an important growth center in craniomaxillofacial skeletogenesis. We crossed Fgfr3ach mice with transgenic mice in which CNP is expressed in the liver under the control of the human serum amyloid-P component promoter, resulting in elevated levels of circulatory CNP ( Fgfr3ach/SAP-Nppc-Tg mice). In the progeny, midfacial hypoplasia in the sagittal direction observed in Fgfr3ach mice was improved significantly by restoring the thickness of synchondrosis and promoting proliferation of chondrocytes in the craniofacial cartilage. In addition, the foramen magnum stenosis observed in Fgfr3ach mice was significantly ameliorated in Fgfr3ach/SAP-Nppc-Tg mice due to enhanced endochondral bone growth of the anterior intraoccipital synchondrosis. These results clearly demonstrate the therapeutic potential of CNP for treatment of midfacial hypoplasia and foramen magnum stenosis in achondroplasia.