Quantitative Muscle Analysis in FSHD Using Whole-Body Fat-Referenced MRI: Composite Scores for Longitudinal and Cross-sectional Analysis.

BACKGROUND AND OBJECTIVES: Facioscapulohumeral muscular dystrophy (FSHD) is a rare, debilitating disease characterized by progressive muscle weakness. MRI is a sensitive assessment of disease severity and progression. We developed a quantitative whole-body (WB) musculoskeletal MRI (WB-MSK-MRI) protocol analyzing muscles in their entirety. This study aimed to assess WB-MSK-MRI as a potential imaging biomarker providing reliable measurements of muscle health that capture disease heterogeneity and clinically meaningful composite assessments correlating with severity and more responsive to change in clinical trials. METHODS: Participants aged 18-65 years, with genetically confirmed FSHD1, clinical severity 2 to 4 (Ricci scale, range 0-5), and ≥1 short tau inversion recovery-positive lower extremity muscle eligible for needle biopsy, enrolled at 6 sites and were imaged twice 4-12 weeks apart. Volumetric analysis of muscle fat infiltration (MFI), muscle fat fraction (MFF), and lean muscle volume (LMV) in 18 (36 total) muscles from bilateral shoulder, proximal arm, trunk, and legs was performed after automated atlas-based segmentation, followed by manual verification. A WB composite score, including muscles at highest risk for progression, and functional cross-sectional composites for correlation with relevant functional outcomes including timed up and go (TUG), FSHD-TUG, and reachable workspace (RWS), were developed. RESULTS: Seventeen participants enrolled in this study; 16 follow-up MRIs were performed at 52 days (range 36-85 days). Functional cross-sectional composites (MFF and MFI) showed moderate to strong correlations: TUG (ρ = 0.71, ρ = 0.83), FSHD-TUG (ρ = 0.73, ρ = 0.73), and RWS (left arm: ρ = -0.71, ρ = -0.53; right arm: ρ = -0.61, ρ = -0.65). WB composite variability: LMVtot, coefficient of variation (CV) 1.9% and 3.4%; MFFtot, within-subject SD (Sw) 0.5% and 1.5%; and MFItot (Sw), 0.3% and 0.4% for normal and intermediate muscles, respectively. CV and Sw were higher in intermediate (MFI ≥0.10; MFF <0.50) than in normal (MFI <0.10, MFF <0.50) muscles. DISCUSSION: We developed a WB-MSK-MRI protocol and composite measures that capture disease heterogeneity and assess muscle involvement as it correlates with FSHD-relevant clinical endpoints. Functional composites robustly correlate with functional assessments. Stability of the WB composite shows that it could be an assessment of change in therapeutic clinical trials. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that quantitative WB-MSK-MRI findings associate with FSHD1 severity measured using established functional assessments.

Evaluating the Use of Medicare Part D in the Veteran Population With Spinal Cord Injury/Disorder.

OBJECTIVE: To examine the different sources of medications, the most common drug classes filled, and the characteristics associated with Medicare Part D pharmacy use in veterans with spinal cord injury/disorder (SCI/D). DESIGN: Retrospective, cross-sectional, observational study. SETTING: Outpatient clinics and pharmacies. PARTICIPANTS: Veterans (N=13,442) with SCI/D using Medicare or Veteran Affairs pharmacy benefits. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Characteristics and top 10 most common drug classes were examined in veterans who (1) used VA pharmacies only; (2) used both VA and Medicare Part D pharmacies; or (3) used Part D pharmacies only. Chi-square tests and multinomial logistic regression analyses were used to determine associations between various patient variables and source of medications. Patient level frequencies were used to determine the most common drug classes. RESULTS: A total of 13,442 veterans with SCI/D were analyzed in this study: 11,788 (87.7%) used VA pharmacies only, 1281 (9.5%) used both VA and Part D pharmacies, and 373 (2.8%) used Part D pharmacies only. Veterans older than 50 years were more likely to use Part D pharmacies, whereas those with traumatic injury, or secondary conditions, were less associated with the use of Part D pharmacies. Opioids were the most frequently filled drug class across all groups. Other frequently used drug classes included skeletal muscle relaxants, gastric medications, antidepressants (other category), anticonvulsants, and antilipemics. CONCLUSIONS: Approximately 12% of veterans with SCI/D are receiving medication outside the VA system. Polypharmacy in this population of veterans is relatively high, emphasizing the importance of health information exchange between systems for improved care for this medically complex population.

Characterization of ectopic colonies that form in widespread areas of the nervous system with neural stem cell transplants into the site of a severe spinal cord injury.

We reported previously the formation of ectopic colonies in widespread areas of the nervous system after transplantation of fetal neural stem cells (NSCs) into spinal cord transection sites. Here, we characterize the incidence, distribution, and cellular composition of the colonies. NSCs harvested from E14 spinal cords from rats that express GFP were treated with a growth factor cocktail and grafted into the site of a complete spinal cord transection. Two months after transplant, spinal cord and brain tissue were analyzed histologically. Ectopic colonies were found at long distances from the transplant in the central canal of the spinal cord, the surface of the brainstem and spinal cord, and in the fourth ventricle. Colonies were present in 50% of the rats, and most rats had multiple colonies. Axons extended from the colonies into the host CNS. Colonies were strongly positive for nestin, a marker for neural precursors, and contained NeuN-positive cells with processes resembling dendrites, GFAP-positive astrocytes, APC/CC1-positive oligodendrocytes, and Ki-67-positive cells, indicating ongoing proliferation. Stereological analyses revealed an estimated 21,818 cells in a colony in the fourth ventricle, of which 1005 (5%) were Ki-67 positive. Immunostaining for synaptic markers (synaptophysin and VGluT-1) revealed large numbers of synaptophysin-positive puncta within the colonies but fewer VGluT-1 puncta. Continuing expansion of NSC-derived cell masses in confined spaces in the spinal cord and brain could produce symptoms attributable to compression of nearby tissue. It remains to be determined whether other cell types with self-renewing potential can also form colonies.

Derivation of oligodendrocyte progenitor cells from human embryonic stem cells.

The directed differentiation of human pluripotent stem cells into specific, determined, and high-purity cell types can provide a means to study the cellular and molecular mechanisms of development and to generate cells for potential therapeutic applications. The ability to derive homogeneous cell populations obviates the need for transgene expression or cell sorting methods and can improve selection efficiency, lineage differentiation, cell viability, and clinical utility. Compared to undifferentiated pluripotent stem cells, high-purity cell phenotypes for clinical therapeutic strategies are expected to enhance engraftment, potentiate clinical efficacy, and decrease the risk of adverse effects such as dedifferentiation or teratoma formation. Clinical interest in the derivation of oligodendrocyte progenitor cells from pluripotent stem cells is based on research that demonstrates the effectiveness of progenitor cell transplants to improve outcomes after spinal cord injury. Here, we describe a protocol to generate oligodendroglial lineage-specific cells in high purity from human embryonic stem cells.

Endogenous remyelination is induced by transplant rejection in a viral model of multiple sclerosis.

Human embryonic stem cell-derived oligodendrocyte progenitors (OPCs) were transplanted into mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus with established demyelination. Engrafted cells did not survive past 2 weeks following transplantation despite treatment with high dose cyclosporine A. While T cell infiltration into the CNS was dampened, elevated numbers of macrophage/microglia and endogenous OPCs were evident surrounding the implantation site and this was associated with increased remyelination. These data suggest that remyelination was initiated by the local response to xenograft transplantation. These findings illustrate the complexities of OPC transplantation into areas of robust immune-mediated pathology.

Derivation of high-purity oligodendroglial progenitors.

Oligodendrocytes are a type of glial cells that play a critical role in supporting the central nervous system (CNS), in particular insulating axons within the CNS by wrapping them with a myelin sheath, thereby enabling saltatory conduction. They are lost, and myelin damaged - demyelination - in a wide variety of neurological disorders. Replacing depleted cell types within demyelinated areas, however, has been shown experimentally to achieve remyelination and so help restore function. One method to produce oligodendrocytes for cellular replacement therapies is through the use of progenitor or stem cells. The ability to differentiate progenitor or stem cells into high-purity fates not only permits the generation of specific cells for transplantation therapies, but also provides powerful tools for studying cellular mechanisms of development. This chapter outlines methods of generating high-purity OPCs from multipotent neonatal progenitor or human embryonic stem cells.