Richard K. Yoon

Clones of Ectopic Stem Cells in the Regeneration of Muscle Defects In Vivo

Little is known about whether clones of ectopic, non-muscle stem cells contribute to muscle regeneration. Stem/progenitor cells that are isolated for experimental research or therapeutics are typically heterogeneous. Non-myogenic lineages in a heterogeneous population conceptually may compromise tissue repair. In this study, we discovered that clones of mononucleated stem cells of human tooth pulp fused into multinucleated myotubes that robustly expressed myosin heavy chain in vitro with or without co-culture with mouse skeletal myoblasts (C2C12 cells). Cloned cells were sustainably Oct4+, Nanog+ and Stro1+. The fusion indices of myogenic clones were approximately 16–17 folds greater than their parent, heterogeneous stem cells. Upon infusion into cardio-toxin induced tibialis anterior muscle defects, undifferentiated clonal progenies not only engrafted and colonized host muscle, but also expressed human dystrophin and myosin heavy chain more efficaciously than their parent heterogeneous stem cell populations. Strikingly, clonal progenies yielded ∼9 times more human myosin heavy chain mRNA in regenerating muscles than those infused with their parent, heterogeneous stem cells. The number of human dystrophin positive cells in regenerating muscles infused with clonal progenies was more than ∼3 times greater than muscles infused with heterogeneous stem cells from which clonal progenies were derived. These findings suggest the therapeutic potential of ectopic myogenic clones in muscle regeneration.

Assessment of Inpatient Fragility Fracture Education and Outpatient Follow-Up at an Urban Tertiary Care Institution

OBJECTIVE To assess the impact of inpatient fragility fracture education on follow-up care at an urban tertiary care center with a multidisciplinary inpatient education and follow-up initiative. METHODS Participants included 139 patients with low energy fragility fractures who were identified, educated, and referred for follow-up by a coordinator. Education consisted of an initial 30 to 40-minute session with the patient and family followed by 10-minute sessions on subsequent hospitalization days. Follow-up activities with primary care physicians (PCPs) and orthopaedic surgeons were documented. RESULTS Of the 129 patients still living at the end of the study period, 74 (57%) had followed up with their PCP while 93 (72%) had returned to see their orthopaedic surgeons. Women were 2.7 times more likely than men to address the cause of the fragility fracture (95% confidence interval [CI], 1.13-6.97; P = .038) and were 6.18 times more likely to receive treatment or to have bone mineral density (BMD) testing (95% CI, 1.29-29.61; P = .023). Patients previously treated for osteoporosis were 3 times more likely to follow-up with their PCPs (95% CI, 1.10-8.02; P = .02), while patients who had previous BMD tests were 4.9 times more likely to follow-up (95% CI, 1.89-12.79; P = .001). We observed a 42% reduction in the likelihood of seeing a physician for osteoporosis evaluation for each additional 10 years of age (95% CI, 13%-61% reduction in odds; P = .008). CONCLUSION In the urban setting, follow-up rates are not sufficiently improved by inpatient education. Improved, persistent communication between the orthopaedic surgeon, PCP, and patient is needed to effectively treat patients and prevent future fractures.

Advances in Pediatric Dentistry

This article addresses advances in 4 key areas related to pediatric dentistry: (1) caries detection tools, (2) early interventions to arrest disease progression, (3) caries-risk assessment tools, and (4) trends in pediatric procedures and dental materials.

Characteristics and Associated Comorbidities of Pediatric Dental Patients Treated under General Anesthesia

OBJECTIVE To describe characteristics and identify common comorbidities of children receiving dental treatment under general anesthesia at Childrens Hospital of New York-Presbyterian. STUDY DESIGN Electronic medical records of all children that received dental treatment under general anesthesia through the Division of Pediatric Dentistry from 2012-2014 were reviewed. Data describing patient characteristics (age, sex, race/ethnicity, insurance carrier, and American Society of Anesthesiologists physical status classification system), medical history, and justification for treatment were collected. Descriptive statistics, including frequencies, percentages and t-tests, were calculated. RESULTS A total of 298 electronic medical records were reviewed, of which 50 records were excluded due to missing information. Of the 248 electronic medical records included, the average age was 5-years-old and 58% were male. The most common reason for dental treatment under general anesthesia was extent and severity of dental disease (53%), followed by significant medical history (47%) and behavior/pre-cooperative age (39%). Those who were ASA III or IV were older (6.6-years) (p<.001). Common medical comorbidities appear evenly distributed: autism (12%), cardiac anomalies (14%), developmental delay (14%), genetic syndromes/chromosomal disorders (13%), and neurological disorders (12%). Younger age groups (1 to 2 years and 3 to 5 years) had a high percentage of hospitalizations due to the extent and severity of the dental disease (83%) and behavior (77%) (p<0.001). CONCLUSIONS No single comorbidity was seen more often than others in this patient population. The range of medical conditions in this population may be a reflection of the range of pediatric specialty services at Childrens Hospital of NewYork-Presbyterian.