Browsing by Author "Emmanuel, Tanusha"
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Item Efficacy of Using Zoledronate for Prevention of Craniofacial Fractures in Mice with Osteogenesis Imperfecta(2024-03-21) Pattillo, Bryce; Miller, Courtney A.; Emmanuel, Tanusha; Crowe, Nicole M.; Menegaz, Rachel A.Osteogenesis imperfecta (OI) is a genetic disorder of type I collagen that results in increased bone fragility, increased fracture rates, and abnormalities of the limbs, vertebral column, and craniofacial skeleton. Long-lasting bisphosphonate drugs, like zoledronate, are used in children with OI to increase bone mineral density and prevent skeletal fractures. Zoledronate increases osteoclast apoptosis, thus reducing relative rates of bone resorption and increasing formation rates. Previous experimental research on the efficacy of zoledronate has focused largely on the postcranial skeleton (e.g. limbs). The goal of this study is to investigate if zoledronate reduces the rate of craniofacial fractures in mice with osteogenesis imperfecta. We hypothesize that mice treated with zoledronate will have fewer skeletal fractures of the skull compared to untreated mice. Mice with OI (OIM, B6C3Fe a/a-Col1a2oim/oim) and unaffected littermates (wild-type, WT) were randomly assigned into either control (C) or zoledronate (ZOL) treatment groups (n=5/genotype/group). Mice treated with zoledronate received subcutaneous injections of the drug (80 µg/kg) at 4, 8, and 12 weeks of age. The craniofacial skeleton of all mice was imaged with a micro-CT scanner (20 µm3 voxels) every 4 weeks from 4-16 weeks. 3D models of the craniofacial skeleton were generated in 3D Slicer software, and analyzed for incidence and location of fractures. At 8 weeks, no fractures were observed in WT-C or WT-ZOL mice. However, fractures were observed in both groups of OIM mice. 80% (4/5 per group) of OIM-C and OIM-ZOL mice had skeletal fractures, and the remaining 20% (1/5 per group) had fractured incisors. All skeletal fractures were observed along the zygomatic arch, proximal to the attachment site of the masseter muscle. Both unilateral and bilateral zygomatic fractures were observed. Preliminary data indicates that a single treatment with zoledronate at 4 weeks of age does not reduce the incidence of craniofacial fractures in mice with OI. Additional data is needed to assess if zoledronate improves fracture healing or bone quality outcomes (e.g. BMD) in the craniofacial skeleton, as has been demonstrated in limb bones. Additionally, the prevalence of fractures proximal to skeletal attachment sites for feeding muscles suggestions that muscle-bone interactions are a key component for understanding the origin of facial fractures in this model. Previous work has shown that long-term use of bisphosphonates like zoledronate may have negative outcomes for the craniofacial skeleton, including delayed bone formation, altered dental eruption, and osteonecrosis of the jaw (ONJ). This study suggests that craniofacial health is an important consideration, distinct from postcranial health, when planning interventions for patients with OI.Item Masticatory muscle morphology in early postnatal mice with osteogenesis imperfecta(2024-03-21) Ansari, Zahra; Miller, Courtney; Emmanuel, Tanusha; Handler, Emma; Gonzales, Lauren; Organ, Jason; Menegaz, Rachel A.Purpose: Osteogenesis imperfecta (OI) is a connective tissue disorder resulting from mutations in COL1A1 or COL1A2, responsible for encoding type I collagen alpha chains. While OI is primarily distinguished by manifestations of bone fragility, including recurrent fractures and bone deformities, muscle abnormalities have also been documented in those affected by OI. While prior research has shown postcranial muscle weakness in mouse models of OI, it remains unclear whether this also applies to feeding musculature and if these differences are present at birth or develop postnatally. This study investigates the development of the masticatory muscles during the early postnatal period in a mouse model. Our hypothesis posits that mice affected by OI will exhibit decreased muscle mass, and therefore potentially weaker muscles, in comparison to unaffected mice. Methods: Cranial tissues from OIM mice (B6C3Fe a/a-Col1a2oim/J) and unaffected wild type (WT) littermates were collected at day of birth (P0) and postnatal day 14 (P14). Tissues were fixed and stained with 1.25% buffered Lugol’s solution, then micro-CT scanned with a reconstruction of 0.02 mm3 voxels. 3D Slicer software was used to isolate and measure the volumes of the superficial masseter, deep masseter, and temporalis muscles. Muscle volumes were compared between genotypes using a Mann-Whitney U test. Results: At birth, no significant differences were observed in body mass or muscle volumes between OIM and WT mice. A trend was observed for OIM mice to have lower superficial masseter volumes compared to WT mice at P0, but this difference was not significant. At P14, OIM mice have significantly lower body weights (p=0.002). Data collection is ongoing for volumetric muscle data from the P14 stage. After birth, body masses diverge rapidly between OIM and WT mice. These growth curves suggest poor feeding performance during the suckling stage in OIM mice. Although masticatory muscle volumes (similar to body mass) start out similar between genotypes at birth, a trend for decreased superficial masseter volume in OIM mice suggests feeding musculature will also lag behind unaffected mice during early postnatal growth. Conclusion: The production of strain above an osteogenic threshold by feeding musculature is critical to typical craniofacial growth during early life. Weaker masticatory muscles may produce lower (yet still osteogenic) levels of strain, contributing to the midfacial hypoplasia seen in OIM mice. A better understanding of muscle development during this critical growth period will provide insight on feeding disorders seen in OI, and the development of the craniofacial phenotype in pediatric patients with OI.Item Pre-weaning craniofacial development in mice with Osteogenesis Imperfecta(2024-03-21) Miller, Courtney; Emmanuel, Tanusha; Gonzales, Lauren; Handler, Emma; Organ, Jason; Menegaz, Rachel A.The craniofacial region plays a pivotal role in various physiological functions, including mastication, speech, and respiration. Early life behaviors have a profound role in shaping adult structure and function. In the early stages of life, all mammals undergo the transition from suckling to mastication, a period coinciding with rapid cranial biomineralization. Osteogenesis imperfecta (OI), a genetic disorder that impacts the production of type I collagen, disrupts biomineralization, leading to craniofacial growth differences affecting overall quality of life. This study investigates the preweaning craniofacial growth trajectory in mice OI (the OIM mouse) compared to unaffected wild type (WT mice). We hypothesize that mice with OI will exhibit smaller overall size and greater craniofacial variation than WT mice due to the abnormal collagen synthesis during skull development. Micro-CT based geometric morphometric analyses of the OIM mouse model (B6C3Fe a/a-Col1a2oim/J) were used to compare craniofacial size and shape differences at birth (P0; n=27 OIM / 20 WT) and postnatal days 7 (P7; n=21/21) and 14 (P14; n=16/20). The SlicerMorph package for 3D Slicer software was used to generate landmark point clouds for the cranium and mandible. Dimension ratios were calculated as width/length for the crania. Principal component analysis with Procrustes ANOVA were used to examine differences between genotypes at each time point, and a canonical variate analysis (CVA) used to identify shape features that maximize the distinction between genotypes across all time points. Results reveal the development of significant differences in both shape and size between the genotypes following birth. At birth, size and shape are similar between genotypes. However, by P7 and P14, OIM mice are significantly (p<0.05) smaller and display pronounced shape changes (p<0.001) characterized by larger neurocranium and shorter viscerocranium. Additionally, OIM mice have significant mandibular alterations by P7 (p<0.001) - shorter ramus, more posterior position of the coronoid, and shorter and wider dental arcade. All of these changes align with the suckling developmental stage, suggesting changes in the ratio of growth between the neurocranium and the viscerocranium during early life. Widening the neurocranium while shortening the viscerocranium during this critical developmental stage alters the masticatory muscle line of action, consequently, influences the health of individuals with OI. These findings underscore the suckling stage’s significance in shaping the foundational structures for later life, providing insights into OI craniofacial development, and suggest potential benefits to directing interventions toward an earlier time point for more effective treatment of OI.