Likelihood of Proceeding to Allogeneic Hematopoietic Cell Transplantation in the United States after Search Activation in the National Registry: Impact of Patient Age, Disease, and Search Prognosis.

The National Marrow Donor Program (NMDP) operates the Be The Match Registry to serve patients who require an allogeneic hematopoietic cell transplant (alloHCT). The factors that result in progression of an active donor search (ie, request for tissue typing or stem cell donation) to alloHCT are poorly understood. Some factors, such as differences in access by ethnic group, are known; however, deeper understanding of other patient and search factors is needed. Our study sought to identify the likelihood of patient progression from initiation of an active search for an unrelated adult donor/umbilical cord blood to transplant and to evaluate factors associated with proceeding to transplantation within 6 months. A retrospective cohort of US donor searches (ie, transplant center's first request of donor/cord blood unit testing; N = 8816) of the Be The Match Registry from January to December 2016 was analyzed. An adult unrelated donor search prognosis score, which categorizes the prognosis of the donor search as good, fair, or poor based on the patient HLA type and race/ethnic group, was included. At 6 months, 3744 (42%) patients had received a transplant. White patients were more likely to receive a transplant (n = 2590 of 5687, 45%) compared to black/African American patients (n = 187 of 700, 27%; P < .001). In multivariate analysis, the adult unrelated donor search prognosis score was associated with proceeding to adult donor or cord blood transplant within 6 months across all patient populations. A poor search prognosis score had an odds ratio (OR) of 0.32 (95% confidence interval [CI], 0.26 to 0.39, P < .001), 0.22 (95% CI, 0.09 to 0.54, P = .001), 0.39 (95% CI, 0.23 to 0.65, P < .001), and 0.26 (95% CI, 0.14 to 0.45, P < .001) for adults with malignant disease, adults with nonmalignant disease, children with malignant disease, and children with nonmalignant disease, respectively. This study identified important factors in the likelihood of a patient proceeding to HCT and suggests areas for future intervention to reduce the barriers to transplant.

Sparing of the extraocular muscles in mdx mice with absent or reduced utrophin expression: A life span analysis.

Sparing of the extraocular muscles in muscular dystrophy is controversial. To address the potential role of utrophin in this sparing, mdx:utrophin(+/-) and mdx:utrophin(-/-) mice were examined for changes in myofiber size, central nucleation, and Pax7-positive and MyoD-positive cell density at intervals over their life span. Known to be spared in the mdx mouse, and contrary to previous reports, the extraocular muscles from both the mdx:utrophin(+/-) and mdx:utrophin(-/-) mice were also morphologically spared. In the mdx:utrophin(+/)(-) mice, which have a normal life span compared to the mdx:utrophin(-/-) mice, the myofibers were larger at 3 and 12 months than the wild type age-matched eye muscles. While there was a significant increase in central nucleation in the extraocular muscles from all mdx:utrophin(+/)(-) mice, the levels were still very low compared to age-matched limb skeletal muscles. Pax7- and MyoD-positive myogenic precursor cell populations were retained and were similar to age-matched wild type controls. These results support the hypothesis that utrophin is not involved in extraocular muscle sparing in these genotypes. In addition, it appears that these muscles retain the myogenic precursors that would allow them to maintain their regenerative capacity and normal morphology over a lifetime even in these more severe models of muscular dystrophy.

Disease course in mdx:utrophin+/- mice: comparison of three mouse models of Duchenne muscular dystrophy.

The mdx mouse model of Duchenne muscular dystrophy (DMD) is used to study disease mechanisms and potential treatments, but its pathology is less severe than DMD patients. Other mouse models were developed to more closely mimic the human disease based on knowledge that upregulation of utrophin has a protective effect in mdx muscle. An mdx:utrophin(-/-) (dko) mouse was created, which had a severe disease phenotype and a shortened life span. An mdx:utrophin(+/-) mouse was also created, which had an intermediate disease phenotype compared to the mdx and dko mice. To determine the usefulness of mdx:utrophin(+/-) mice for long-term DMD studies, limb muscle pathology and function were assessed across the life span of wild-type, mdx, mdx:utrophin(+/-), and dko mice. Muscle function assessment, specifically grip duration and rotarod performance, demonstrated that mdx:utrophin(+/-) mice were weaker for a longer time than mdx mice. Mean myofiber area was smaller in mdx:utrophin(+/-) mice compared to mdx mice at 12 months. Mdx:utrophin(+/-) mice had a higher percentage of centrally nucleated myofibers compared to mdx mice at 6 and 12 months. Collagen I and IV density was significantly higher in mdx:utrophin(+/-) muscle compared to mdx at most ages examined. Generally, mdx:utrophin(+/-) mice showed an intermediate disease phenotype over a longer time course compared to the mdx and dko mice. While they do not genetically mirror human DMD, mdx:utrophin(+/-) mice may be a more useful animal model than mdx or dko mice for investigating long-term efficacy of potential treatments when fibrosis or muscle function is the focus.

Dystrophic changes in extraocular muscles after gamma irradiation in mdx:utrophin(+/-) mice.

Extraocular muscles (EOM) have a strikingly different disease profile than limb skeletal muscles. It has long been known that they are spared in Duchenne (DMD) and other forms of muscular dystrophy. Despite many studies, the cause for this sparing is not understood. We have proposed that differences in myogenic precursor cell properties in EOM maintain normal morphology over the lifetime of individuals with DMD due to either greater proliferative potential or greater resistance to injury. This hypothesis was tested by exposing wild type and mdx:utrophin(+/-) (het) mouse EOM and limb skeletal muscles to 18 Gy gamma irradiation, a dose known to inhibit satellite cell proliferation in limb muscles. As expected, over time het limb skeletal muscles displayed reduced central nucleation mirrored by a reduction in Pax7-positive cells, demonstrating a significant loss in regenerative potential. In contrast, in the first month post-irradiation in the het EOM, myofiber cross-sectional areas first decreased, then increased, but ultimately returned to normal compared to non-irradiated het EOM. Central nucleation significantly increased in the first post-irradiation month, resembling the dystrophic limb phenotype. This correlated with decreased EECD34 stem cells and a concomitant increase and subsequent return to normalcy of both Pax7 and Pitx2-positive cell density. By two months, normal het EOM morphology returned. It appears that irradiation disrupts the normal method of EOM remodeling, which react paradoxically to produce increased numbers of myogenic precursor cells. This suggests that the EOM contain myogenic precursor cell types resistant to 18 Gy gamma irradiation, allowing return to normal morphology 2 months post-irradiation. This supports our hypothesis that ongoing proliferation of specialized regenerative populations in the het EOM actively maintains normal EOM morphology in DMD. Ongoing studies are working to define the differences in the myogenic precursor cells in EOM as well as the cellular milieu in which they reside.

Sparing of extraocular muscle in aging and muscular dystrophies: a myogenic precursor cell hypothesis.

The extraocular muscles (EOM) are spared from pathology in aging and many forms of muscular dystrophy. Despite many studies, this sparing remains an enigma. The EOM have a distinct embryonic lineage compared to somite-derived muscles, and we have shown that they continuously remodel throughout life, maintaining a population of activated satellite cells even in aging. These data suggested the hypothesis that there is a population of myogenic precursor cells (mpcs) in EOM that is different from those in limb, with either elevated numbers of stem cells and/or mpcs with superior proliferative capacity compared to mpcs in limb. Using flow cytometry, EOM and limb muscle mononuclear cells were compared, and a number of differences were seen. Using two different cell isolation methods, EOM have significantly more mpcs per mg muscle than limb skeletal muscle. One specific subpopulation significantly increased in EOM compared to limb was positive for CD34 and negative for Sca-1, M-cadherin, CD31, and CD45. We named these the EOMCD34 cells. Similar percentages of EOMCD34 cells were present in both newborn EOM and limb muscle. They were retained in aged EOM, whereas the population decreased significantly in adult limb muscle and were extremely scarce in aged limb muscle. Most importantly, the percentage of EOMCD34 cells was elevated in the EOM from both the mdx and the mdx/utrophin(-/-) (DKO) mouse models of DMD and extremely scarce in the limb muscles of these mice. In vitro, the EOMCD34 cells had myogenic potential, forming myotubes in differentiation media. After determining a media better able to induce proliferation in these cells, a fusion index was calculated. The cells isolated from EOM had a 40% higher fusion index compared to the same cells isolated from limb muscle. The EOMCD34 cells were resistant to both oxidative stress and mechanical injury. These data support our hypothesis that the EOM may be spared in aging and in muscular dystrophies due to a subpopulation of mpcs, the EOMCD34 cells, that are retained in significantly higher percentages in normal, mdx and DKO mice EOM, appear to be resistant to elevated levels of oxidative stress and toxins, and actively proliferate throughout life. Current studies are focused on further defining the EOMCD34 cell subtype molecularly, with the hopes that this may shed light on a cell type with potential therapeutic use in patients with sarcopenia, cachexia, or muscular dystrophy.

Intranasal delivery of neurotrophic factors BDNF, CNTF, EPO, and NT-4 to the CNS.

Injury to the central nervous system (CNS) generally results in significant neuronal death and functional loss. In vitro experiments have demonstrated that neurotrophic factors such as brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), and neurotrophin-4/5 (NT-4/5) can promote neuronal survival. However, delivery to the injured CNS is difficult as these large protein molecules do not efficiently cross the blood-brain barrier. Intranasal delivery of 70 microg [(125)I]-radiolabeled BDNF, CNTF, NT-4, or erythropoietin (EPO) resulted in 0.1-1.0 nM neurotrophin concentrations within 25 min in brain parenchyma. In addition, not only did these neurotrophic factors reach the CNS, they were present in sufficient concentrations to activate the prosurvival PI3Kinase/Akt pathway, even where lower levels of neurotrophic factors were measured. Currently traumatic, ischemic and compressive injuries to the CNS have no effective treatment. There is potential clinical relevancy of this method for rescuing injured CNS tissues in order to maintain CNS function in affected patients. The intranasal delivery method has great clinical potential due to (1) simplicity of administration, (2) noninvasive drug administration, (3) relatively rapid CNS delivery, (4) ability to repeat dosing easily, (5) no requirement for drug modification, and (6) minimal systemic exposure.