Involvement of BCR::ABL1 in laminin adhesion of Philadelphia chromosome-positive acute lymphoblastic leukemia through upregulation of integrin α6

BACKGROUND

Adhesion of cancer cells to extracellular matrix laminin through the integrin superfamily reportedly induces drug resistance. Heterodimers of integrin α6 (CD49f) with integrin β1 (CD29) or β4 (CD104) are major functional receptors for laminin. Higher CD49f expression is reportedly associated with a poorer response to induction therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Moreover, a xenograft mouse model transplanted with primary BCP-ALL cells revealed that neutralized antibody against CD49f improved survival after chemotherapy.

AIMS

Considering the poor outcomes in Philadelphia chromosome (Ph)-positive ALL treated with conventional chemotherapy without tyrosine kinase inhibitors, we sought to investigate an involvement of the laminin adhesion.

METHODS AND RESULTS

Ph-positive ALL cell lines expressed the highest levels of CD49f among the BCP-ALL cell lines with representative translocations, while CD29 and CD104 were ubiquitously expressed in BCP-ALL cell lines. The association of Ph-positive ALL with high levels of CD49f gene expression was also confirmed in two databases of childhood ALL cohorts. Ph-positive ALL cell lines attached to laminin and their laminin-binding properties were disrupted by blocking antibodies against CD49f and CD29 but not CD104. The cell surface expression of CD49f, but not CD29 and CD104, was downregulated by imatinib treatment in Ph-positive ALL cell lines, but not in their T315I-acquired sublines. Consistently, the laminin-binding properties were disrupted by the imatinib pre-treatment in the Ph-positive ALL cell line, but not in its T315I-acquired subline.

CONCLUSION

BCR::ABL1 plays an essential role in the laminin adhesion of Ph-positive ALL cells through upregulation of CD49f.

A Model to Study Wound Healing Over Exposed Avascular Structures in Rodents With a 3D-Printed Wound Frame

BACKGROUND

Soft tissue defects with exposed avascular structures require reconstruction with well-vascularized tissues. Extensive research is ongoing to explore tissue engineered products that provide durable coverage. However, there is a lack of controlled and affordable testbeds in the preclinical setting to reflect this challenging clinical scenario. We aimed to address this gap in the literature and develop a feasible and easily reproducible model in rodents that reflects an avascular structure in the wound bed.

METHODS

We created 20 × 20 mm full thickness wounds on the dorsal skin of Lewis rats and secured 0.5-mm-thick silicone sheets of varying sizes to the wound bed. A 3D-printed wound frame was designed to isolate the wound environment. Skin graft and free flap survival along with exposure of the underlying silicone was assessed. Rats were followed for 4 weeks with weekly dressing changes and photography. Samples were retrieved at the endpoint for tissue viability and histologic analysis.

RESULTS

The total wound surface area was constant throughout the duration of the experiment in all groups and the wound frames were well tolerated. The portion of the skin graft without underlying silicone demonstrated integration with the underlying fascia and a histologically intact epidermis. Gradual necrosis of the portion of the skin graft overlying the silicone sheet was observed with varying sizes of the silicone sheet. When the size of the silicone sheet was reduced from 50% of the wound surface area, the portion surviving over the silicone sheet increased at the 4-week timepoint. The free flap provided complete coverage over the silicone sheet.

CONCLUSION

We developed a novel model of rodent wound healing to maintain the same wound size and isolate the wound environment for up to 4 weeks. This model is clinically relevant to a complex wound with an avascular structure in the wound bed. Skin grafts failed to completely cover increasing sizes of the avascular structure, whereas the free flap was able to provide viable coverage. This cost-effective model will establish an easily reproducible platform to evaluate more complex bioengineered wound coverage solutions.

Machine Perfusion Deters Ischemia-Related Derangement of a Rodent Free Flap: Development of a Model

INTRODUCTION

Machine perfusion can enable isolated support of composite tissues, such as free flaps. The goal of perfusion in this setting is to preserve tissues prior to transplantation or provide transient support at the wound bed. This study aimed to establish a rodent model of machine perfusion in a fasciocutaneous-free flap to serve as an affordable testbed and determine the potential of the developed support protocol to deter ischemia-related metabolic derangement.

METHODS

Rat epigastric-free flaps were harvested and transferred to a closed circuit that provides circulatory and respiratory support. Whole rat blood was recirculated for 8 h, while adjusting the flow rate to maintain arterial-like perfusion pressures. Blood samples were collected during support. Extracellular tissue lactate and glucose levels were characterized with a microdialysis probe and compared with warm ischemic, cold ischemic, and anastomosed-free flap controls.

RESULTS

Maintenance of physiologic arterial pressures (85-100 mmHg) resulted in average pump flow rates of 360-430 μL/min. Blood-based measurements showed maintained glucose and oxygen consumption throughout machine perfusion. Average normalized lactate to glucose ratio for the perfused flaps was 5-32-fold lower than that for the warm ischemic flap controls during hours 2-8 (P < 0.05).

CONCLUSIONS

We developed a rat model of ex vivo machine perfusion of a fasciocutaneous-free flap with maintained stable flow and tissue metabolic activity for 8 h. This model can be used to assess critical elements of support in this setting as well as explore other novel therapies and technologies to improve free tissue transfer.

Local Delivery of Adipose Stem Cells Promotes Allograft Survival in a Rat Hind-Limb Model of Vascularized Composite Allotransplantation

BACKGROUND

Adipose stem cells (ASCs) are a promising cell-based immunotherapy because of their minimally invasive harvest, high yield, and immunomodulatory capacity. In this study, the authors investigated the effects of local versus systemic ASC delivery on vascularized composite allotransplant survival and alloimmune regulation.

METHODS

Lewis rats received hind-limb transplants from Brown Norway rats and were administered donor-derived ASCs (passage 3 or 4, 1 × 10 6 cells/rat) locally in the allograft, or contralateral limb, or systemically at postoperative day 1. Recipients were treated intraperitoneally with rabbit anti-rat lymphocyte serum on postoperative days 1 and 4 and daily tacrolimus for 21 days. Limb allografts were monitored for clinical signs of rejection. Donor cell chimerism, immune cell differentiation, and cytokine expression in recipient lymphoid organs were measured by flow cytometric analysis. The immunomodulation function of ASCs was tested by mixed lymphocyte reaction assay and ASC stimulation studies.

RESULTS

Local-ASC-treated recipients achieved significant prolonged allograft survival (85.7% survived >130 days; n = 6) compared with systemic-ASC and contralateral-ASC groups. Secondary donor skin allografts transplanted to the local-ASC long-term surviving recipients accepted permanently without additional immunosuppression. The increases in donor cell chimerism and regulatory T-cells were evident in blood and draining lymph nodes of the local-ASC group. Moreover, mixed lymphocyte reaction showed that ASCs inhibited donor-specific T-cell proliferation independent of direct ASC-T-cell contact. ASCs up-regulated antiinflammatory molecules in response to cytokine stimulation in vitro.

CONCLUSION

Local delivery of ASCs promoted long-term survival and modulated alloimmune responses in a full major histocompatibility complex-mismatched vascularized composite allotransplantation model and was more effective than systemic administration.

CLINICAL RELEVANCE STATEMENT

ASCs are a readily available and abundant source of therapeutic cells that could decrease the amount of systemic immunosuppression required to maintain limb and face allografts.

Biodegradable Nerve Guide with Glial Cell Line-Derived Neurotrophic Factor Improves Recovery After Facial Nerve Injury in Rats

Background: Bioengineered nerve guides with glial cell line-derived neurotrophic factor (GDNF) support recovery after facial nerve injury by acting as regenerative scaffolds. Objective: To compare functional, electrophysiological, and histological outcomes after repair of rat facial nerve transection in control, empty nerve guide, and nerve guide with GDNF conditions. Methods: Rats underwent transection and primary repair of the buccal branch of the facial nerve and were divided into (1) transection and repair only, (2) transection and repair augmented with empty guide, (3) transection and repair augmented with GDNF-guide groups. Weekly measurements of the whisking movements were recorded. At 12 weeks, compound muscle action potentials (CMAPs) at the whisker pad were assessed, and samples were collected for histomorphometric analysis. Results: Rats in GDNF-guide group displayed the earliest peak in normalized whisking amplitude. CMAPs were significantly higher after GDNF-guide placement. Mean fiber surface area of the target muscle, axonal count of the injured branch, and the number of Schwann cells were highest with GDNF guides. Conclusion: The biodegradable nerve guide containing double-walled GDNF microspheres enhanced recovery after facial nerve transection and primary repair.

Automated Decellularization of the Rodent Epigastric Free Flap: A Comparison of Sodium Dodecyl Sulfate-Based Protocols

BACKGROUND

 Free tissue transfer to cover complex wounds with exposed critical structures results in donor-site morbidity. Perfusion decellularization and recellularization of vascularized composite tissues is an active area of research to fabricate complex constructs without a donor site. Sodium dodecyl sulfate (SDS)-based protocols remain the predominant choice for decellularization despite the deleterious effects on tissue ultrastructure and capillary networks. We aimed to develop an automated decellularization process and compare different SDS perfusion times to optimize the protocol.

METHODS

 A three-dimensional-printed closed-system bioreactor capable of continuously perfusing fluid through the vasculature was used for decellularization. The artery and vein of rat epigastric fasciocutaneous free flaps were cannulated and connected to the bioreactor. Protocols had varying durations of 1% SDS solution (3, 5, and 10 days) followed by 1 day of 1% Triton X-100 and 1 day of 1x phosphate-buffered saline. The residual DNA was quantified. Microarchitecture of the constructs was assessed with histology, and the vascular network was visualized for qualitative assessment.

RESULTS

 The structural integrity and the microarchitecture of the extracellular matrix was preserved in the 3- and 5-day SDS perfusion groups; however, the subcutaneous tissue of the 10-day protocol lost its structure. Collagen and elastin structures of the pedicle vessels were not compromised by the decellularization process. Five-day SDS exposure group had the least residual DNA content (p < 0.001). Across all protocols, skin consistently had twice as much residual DNA over the subcutaneous tissues.

CONCLUSION

 A compact and integrated bioreactor can automate decellularization of free flaps to bioengineer regenerative constructs for future use in reconstruction of complex defects. A decellularization protocol with 5 days of 1% SDS exposure was the most successful to keep the residual DNA content at a minimum while preserving the structural integrity of the tissues.

CRISPR/Cas9-Mediated Induction of Relapse-Specific NT5C2 and PRPS1 Mutations Confers Thiopurine Resistance as a Relapsed Lymphoid Leukemia Model

6-Mercaptopurine (6-MP) is a key component in maintenance therapy for childhood acute lymphoblastic leukemia (ALL). Recent next-generation sequencing analysis of childhood ALL clarified the emergence of the relapse-specific mutations of the NT5C2 and PRPS1 genes, which are involved in thiopurine metabolism. In this scenario, minor clones of leukemia cells could acquire the 6-MP-resistant phenotype as a result of the NT5C2 or PRPS1 mutation during chemotherapy (including 6-MP treatment) and confer disease relapse after selective expansion. Thus, to establish new therapeutic modalities overcoming 6-MP resistance in relapsed ALL, human leukemia models with NT5C2 and PRPS1 mutations in the intrinsic genes are urgently required. Here, mimicking the initiation process of the above clinical course, we sought to induce two relapse-specific hotspot mutations (R39Q mutation of the NT5C2 gene and S103N mutation of the PRPS1 gene) into a human lymphoid leukemia cell line by homologous recombination (HR) using the CRISPR/Cas9 system. After 6-MP selection of the cells transfected with Cas9 combined with single-guide RNA and donor DNA templates specific for either of those two mutations, we obtained the sublines with the intended NT5C2-R39Q and PRPS1-S103N mutation as a result of HR. Moreover, diverse in-frame small insertion/deletions were also confirmed in the 6-MP-resistant sublines at the target sites of the NT5C2 and PRPS1 genes as a result of nonhomologous end joining. These sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations in the 6-MP sensitivity and development of therapy overcoming the thiopurine resistance of leukemia cells. SIGNIFICANCE STATEMENT: Mimicking the initiation process of relapse-specific mutations of the NT5C2 and PRPS1 genes in childhood acute lymphoblastic leukemia treated with 6-mercaptopurine (6-MP), this study sought to introduce NT5C2-R39Q and PRPS1-S103N mutations into a human lymphoid leukemia cell line by homologous recombination using the CRISPR/Cas9 system. In the resultant 6-MP-resistant sublines, the intended mutations and diverse in-frame small insertions/deletions were confirmed, indicating that the obtained sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations.

Creation of Philadelphia chromosome by CRISPR/Cas9-mediated double cleavages on BCR and ABL1 genes as a model for initial event in leukemogenesis

The Philadelphia (Ph) chromosome was the first translocation identified in leukemia. It is supposed to be generated by aberrant ligation between two DNA double-strand breaks (DSBs) at the BCR gene located on chromosome 9q34 and the ABL1 gene located on chromosome 22q11. Thus, mimicking the initiation process of translocation, we induced CRISPR/Cas9-mediated DSBs simultaneously at the breakpoints of the BCR and ABL1 genes in a granulocyte-macrophage colony-stimulating factor (GM-CSF) dependent human leukemia cell line. After transfection of two single guide RNAs (sgRNAs) targeting intron 13 of the BCR gene and intron 1 of the ABL1 gene, a factor-independent subline was obtained. In the subline, p210 BCR::ABL1 and its reciprocal ABL1::BCR fusions were generated as a result of balanced translocation corresponding to the Ph chromosome. Another set of sgRNAs targeting intron 1 of the BCR gene and intron 1 of the ABL1 gene induced a factor-independent subline expressing p190 BCR::ABL1. Both p210 and p190 BCR::ABL1 induced factor-independent growth by constitutively activating intracellular signaling pathways for transcriptional regulation of cell cycle progression and cell survival that are usually regulated by GM-CSF. These observations suggested that simultaneous DSBs at the BCR and ABL1 gene breakpoints are initiation events for oncogenesis in Ph+ leukemia. (200/200 words).

Glucocorticoid receptor gene mutations confer glucocorticoid resistance in B-cell precursor acute lymphoblastic leukemia

Glucocorticoid (GC) is a key drug in the treatment of B-cell precursor acute lymphoblastic leukemia (BCP-ALL), and the initial GC response is an important prognostic factor. GC receptors play an essential role in GC sensitivity, and somatic mutations of the GC receptor gene, NR3C1, are reportedly identified in some BCP-ALL cases, particularly at relapse. Moreover, associations of somatic mutations of the CREB-binding protein (CREBBP) and Wolf-Hirschhorn syndrome candidate 1 (WHSC1) genes with the GC-resistance of ALL have been suggested. However, the significance of these mutations in the GC sensitivity of BCP-ALL remains to be clarified in the intrinsic genes. In the present study, we sequenced NR3C1, WHSC1, and CREBBP genes in 99 BCP-ALL and 22 T-ALL cell lines (32 and 67 cell lines were known to be established at diagnosis and at relapse, respectively), and detected their mutations in 19 (2 cell lines at diagnosis and 15 cell lines at relapse), 26 (6 and 15), and 38 (11 and 15) cell lines, respectively. Of note, 14 BCP-ALL cell lines with the NR3C1 mutations were significantly more resistant to GC than those without mutations. In contrast, WHSC1 and CREBBP mutations were not associated with GC resistance. However, among the NR3C1 unmutated BCP-ALL cell lines, WHSC1 mutations tended to be associated with GC resistance and lower NR3C1 gene expression. Finally, we successfully established GC-resistant sublines of the GC-sensitive BCP-ALL cell line (697) by disrupting ligand binding and DNA binding domains of the NR3C1 gene using the CRISPR/Cas9 system. These observations demonstrated that somatic mutations of the NR3C1 gene, and possibly the WHSC1 gene, confer GC resistance in BCP-ALL.

In vivo MRI evaluation of anterograde manganese transport along the visual pathway following whole eye transplantation

BACKGROUND

Since adult mammalian retinal ganglion cells cannot regenerate after injury, we have recently established a whole-eye transplantation (WET) rat model that provides an intact optical system to investigate potential surgical restoration of irreversible vision loss. However, it remains to be elucidated whether physiological axoplasmic transport exists in the transplanted visual pathway. New Method: We developed an in vivo imaging model system to assess WET integration using manganese-enhanced magnetic resonance imaging (MEMRI) in rats. Since Mn²⁺ is a calcium analogue and an active T1-positive contrast agent, the levels of anterograde manganese transport can be evaluated in the visual pathways upon intravitreal Mn²⁺ administration into both native and transplanted eyes.

RESULTS

 No significant intraocular pressure difference was found between native and transplanted eyes, whereas comparable manganese enhancement was observed between native and transplanted intraorbital optic nerves, suggesting the presence of anterograde manganese transport after WET. No enhancement was detected across the coaptation site in the higher visual areas of the recipient brain. Comparison with Existing Methods: Existing imaging methods to assess WET focus on either the eye or local optic nerve segments without direct visualization and longitudinal quantification of physiological transport along the transplanted visual pathway, hence the development of in vivo MEMRI.

CONCLUSION

 Our established imaging platform indicated that essential physiological transport exists in the transplanted optic nerve after WET. As neuroregenerative approaches are being developed to connect the transplanted eye to the recipient's brain, in vivo MEMRI is well-suited to guide strategies for successful WET integration for vision restoration. Keywords (Max 6): Anterograde transport, magnetic resonance imaging, manganese, neuroregeneration, optic nerve, whole-eye transplantation.

Intramuscular injection of skeletal muscle derived extracellular matrix mitigates denervation atrophy after sciatic nerve transection

Peripheral nerve injury and the associated muscle atrophy has an estimated annual healthcare burden of $150 billion dollars in the United States. When considering the total annual health-related spending of $3.5 trillion, these pathologies alone occupy about 4.3%. The prevalence of these ailments is rooted, at least in part, in the lack of specific preventative therapies that can be administered to muscle while it remains in the denervated state. To address this, skeletal muscle-derived ECM (skECM) was injected directly in denervated muscle with postoperative analysis performed at 20 weeks, including gait analysis, force production, cytokine quantification, and histological analysis. skECM was shown to be superior against non-injected muscle controls showing no difference in contraction force to uninjured muscle at 20 weeks. Cytokines IL-1β, IL-18, and IFNγ appeared to mediate regeneration with statistical regression implicating these cytokines as strong predictors of muscle contraction, showing significant linear correlation.

QS4: Optimizing The Decellularization Of The Rodent Epigastric Free Flap: A Comparison Of Automated SDS-based Protocols

Purpose:

Methods:

Results:

Conclusion:

Evaluation of Porcine Versus Human Mesenchymal Stromal Cells From Three Distinct Donor Locations for Cytotherapy

Background: Mesenchymal stromal cell (MSC)-based cytotherapies fuel the hope for reduction of chronic systemic immunosuppression in allotransplantation, and our group has previously shown this capability for both swine and human cells. MSCs harvested from distinct anatomical locations may have different behavior and lead to different outcomes in both preclinical research and human trials. To provide an effective reference for cell therapy studies, we compared human and porcine MSCs from omental fat (O-ASC), subcutaneous fat (SC-ASC) and bone marrow (BM-MSC) under rapid culture expansion with endothelial growth medium (EGM).

Methods: MSCs isolated from pigs and deceased human organ donors were compared for yield, viability, cell size, population doubling times (PDT), surface marker expression and differentiation potential after rapid expansion with EGM. Immunosuppressant toxicity on MSCs was investigated in vitro for four different standard immunosuppressive drugs. Immunomodulatory function was compared in mixed lymphocyte reaction assays (MLR) with/without immunosuppressive drug influence.

Results: Human and porcine omental fat yielded significantly higher cell numbers than subcutaneous fat. Initial PDT was significantly shorter in ASCs than BM-MSCs and similar thereafter. Viability was reduced in BM-MSCs. Porcine MSCs were positive for CD29, CD44, CD90, while human MSCs expressed CD73, CD90 and CD105. All demonstrated confirmed adipogenic differentiation capacity. Cell sizes were comparable between groups and were slightly larger in human cells. Rapamycin revealed slight, mycophenolic acid strong and significant dose-dependent toxicity on viability/proliferation of almost all MSCs at therapeutic concentrations. No relevant toxicity was found for Tacrolimus and Cyclosporin A. Immunomodulatory function was dose-dependent and similar between groups. Immunosuppressants had no significant adverse effect on MSC immunomodulatory function.

Discussion: MSCs from different harvest locations and donor species differ in terms of isolation yields, viability, PDT, and size. We did not detect relevant differences in immunomodulatory function with or without the presence of immunosuppressants. Human and pig O-ASC, SC-ASC and BM-MSC share similar immunomodulatory function in vitro and warrant confirmation in large animal studies. These findings should be considered in preclinical and clinical MSC applications.

The Ocular Immune Response in a Rodent Model of Whole Eye Transplantation

Introduction

Approximately 36 million people are totally blind globally. Using a rodent whole eye orthotopic transplant model (WET), we are investigating a potential clinical treatment to restore vision. Typically, clinical transplantation involves allogeneic individuals and immune rejection is the first obstacle after surgery. Her--e, we use an MHC class I and II mismatched transplant model without immunosuppression to describe for the first time the features of the immune reaction in WET.

Methods

14-wk old male Brown Norway (BN) rats served as donor and recipient in the syngeneic group. 14-wk old male BN rats served as donors with age/sex matched Lewis rats used as recipient in the allogeneic group. Both groups underwent WET, subsequently the transplanted eye blood supply and structure were evaluated on post-operative day (POD) 2 by optical coherence tomography (OCT). Skin and cornea rejection at POD 2,4,5,6,8 were assessed separately by a scoring system. The progressive infiltration of immune cells into the eye was evaluated by flow cytometry and histology.

Results

At POD5 allogeneic corneas had transparency changes that coincided with skin rejection and Cornea thickness dramatically increased by 150% over syngeneic eyes. Also, the allogeneic group had significant CD4+, CD8+ T cells and NK cell infiltration in aqueous humor, iris, retina and choroid with no difference in cornea.

Conclusion

These preliminary results indicate that acute rejection in WET is T cell mediated and the blood ocular barrier is compromised post-operatively, where immune cells can access the eye. Rejection after WET can be potentially monitored by noninvasive measurement of the cornea thickness or easily accessible aqueous humor.

Biopatterned CTLA4/Fc Matrices Facilitate Local Immunomodulation, Engraftment, and Glucose Homeostasis After Pancreatic Islet Transplantation

Pancreatic islet transplantation (PIT) represents a potential therapy to circumvent the need for exogenous insulin in type 1 diabetes. However, PIT remains limited by lack of donor islets and the need for long-term multidrug immunosuppression to prevent alloimmune islet rejection. Our goal was to evaluate a local immunoregulatory strategy that sustains islet allograft survival and restores glucose homeostasis in the absence of systemic immunosuppression. Nanogram quantities of murine CTLA4/Fc fusion protein were controllably delivered within human acellular dermal matrix scaffolds using an inkjet-based biopatterning technology and cotransplanted with allogeneic islets under the renal capsule to create an immunoregulatory microenvironment around the islet allograft. We achieved long-term engraftment of small loads of allogeneic islet cells with 40% of MHC-mismatched mouse recipients maintaining sustained normoglycemia following pancreatic β-cell ablation by streptozotocin. Biopatterned CTLA4/Fc local therapy was associated with expansion of Foxp3⁺ regulatory T cells and shifts in cytokine production and gene expression from proinflammatory to regulatory profiles, thus substantially benefiting islet allografts survival and function. This study is a new paradigm for targeted therapies in PIT that demonstrates the favorable effects of immune alterations in the transplant milieu and suggests a unique strategy for minimizing systemic immunosuppression and promoting islet allograft survival.

Ethical Considerations of Whole-Eye Transplantation

Whole eye transplantation (WET) remains experimental. Long presumed impossible, recent scientific advances regarding WET suggest that it may become a clinical reality. However, the ethical implications of WET as an experimental therapeutic strategy remain largely unexplored. This article evaluates the ethical considerations surrounding WET as an emerging experimental treatment for vision loss. A thorough review of published literature pertaining to WET was performed; ethical issues were identified during review of the articles.

Establishing donor specific tolerance in vascularized composite allotransplantation via local enrichment of endogenous regulatory T cells (TRAN3P.865)

Vascularized composite allotransplantation (VCA)—encompassing transplantation of hands/limbs and face is an emerging field with potential to restore the appearance and function of damaged tissue. Clinically, the process of rejection is suppressed via systemic immunosuppression, which is associated with a host of deleterious side effects. An alternative approach to prevent rejection is to harness the homeostatic mechanisms intrinsic to the immune system. To this end our group has recently developed controlled release microparticle (MP) systems capable of enriching Tregs at given location via synthetic cell constructs referred to as Expansion MP. Accordingly, we hypothesized that Treg enriching systems that release key cytokines, and immunosuppressive agents, can promote long term graft survival in preclinical VCA models. Following fabrication, Expansion MP was tested in an allogeneic rat hind limb transplant model and then in a swine gracilis myocutaneous flap allotransplant model. Following subcutaneous injection of microparticles, rodent hind limbs survived indefinitely (&gt;200 days) and swine allografts survived until the end of the study period (4 weeks) with no signs of rejection. Secondary skin grafts and MLRs in both models demonstrate that ExpansionMP treatment appears to confer donor specific tolerance to recipients. Given these promising results, we believe this technology has the potential to dramatically impact the field of VCA and reconstructive transplantation.

Detection of Giardia lamblia cysts in non-fixed long-term stored human feces by direct immunofluorescence assay

Giardia lamblia cysts in fecal specimens are detected by conventional morphological methods. The direct immunofluorescence monoclonal antibody assay (DFA) is also applied to detect G. lamblia cysts in feces, but little is known about the usefulness of DFA in fecal specimens stored under various conditions. The aim of the present study was to evaluate the DFA for detection of G. lamblia cysts and to compare these results with the direct smear method in long-term storage of non-fixed fecal specimens. Fecal specimens with G. lamblia cysts were stored in a refrigerator at 5 degrees C(14 samples), a freezer at -20 degrees C (9 samples), or in 3.9% formalin-saline solution at room temperature (28 samples). G. lamblia cysts were detected by DFA in all stored specimens, while they were detected in only 56% of refrigerated and 93% of frozen specimens by the direct smear method. The storage period of all samples testing negative by direct smear was more than 24 months. Many degenerated cysts were recognized by DFA when cysts were negative by the direct smear method. Our results indicate that DFA is a useful method for detecting G. lamblia cysts in fecal samples that have undergone long-term storage.

Dexamethasone down-regulates the expression of endothelin B receptor mRNA in the rat brain

The present study was designed to examine effects of dexamethasone on the steady state level of endothelin B(ETB) receptor mRNA in in vivo the rat brain. ETB receptor mRNA was very high at the hypothalamus and cerebellum but was comparatively low at the striatum and amygdala. Dexamethasone, 1 and 7 mg/kg, i.p., markedly and dose-relatedly decreased ETB receptor mRNA level with slow onset of 8hr at the hypothalamus and cerebellum, but did not induced a marked decrease at other areas. On the contrary, dexamethasone produced an increase of ET-1 mRNA which preceded to the decrease of ETB receptor mRNA at the same brain areas. Phosphoramidon, a endothelin-converting enzyme inhibitor, did not antagonized but potentiated the effect of dexamethasone. Besides, phosphoramidon per se markedly stimulated the expression of ET-1 mRNA. The results suggested that dexamethasone down-regulates ETB receptor mRNA level at the hypothalamus and cerebellum of rat brain and these effects may be involved in the increase of ET-1 peptide gene transcription.

Patterns of interruption of atrial flutter induced by rapid atrial pacing

We evaluated the patterns of interruption of atrial flutter (AFl) induced by rapid atrial pacing in 10 patients using standard electrophysiologic techniques. We observed 3 patterns of interruption of AFl: 1) interruption resulting from block of an orthodromic wavefront within the reentry loop in 5 patients; 2) interruption when pacing impulses no longer captured all of the recording sites in the atrium during rapid atrial pacing in 2 patients, and 3) interruption with 1 echo wave after the cessation of pacing in 3 patients. These findings suggest that there are patterns of interruption of AFl other than that resulting from a simple block of an orthodromic wavefront within the reentry loop.

Developmental differences of angiotensinogen mRNA in the preoptic area between spontaneously hypertensive and age-matched Wistar-Kyoto rats

In order to know the possible involvement of the central angiotensin system in hypertension, angiotensinogen mRNA (AomRNA) levels of eight discrete brain areas were measured by Northern blot hybridization analysis in the spontaneously hypertensive rats (SHR), compared with those in age-matched normotensive Wistar-Kyoto rats (WKY). In 16-week-old SHR (hypertensive stage), AomRNA levels in the preoptic area (POA), but not in the ventromedial hypothalamus, lateral hypothalamus and mammillary body, among the hypothalamic nuclei, were higher (approximate 50%) than in WKY. There were no differences in other brain areas, such as the striatum, septum, amygdala and cerebellum between both the strains. The AomRNA levels in POA were already higher (38%) in 4-week-old SHR (prehypertensive stage) without significance, and the difference was augmented (82%) in 7-week-old SHR (evolving stage). These results suggest that the developmental changes of AomRNA levels at POA may be related in some aspect to hypertension process.

[A case of repetitive monomorphic ventricular tachycardia]

We present a case treated with aprindine and metoprolol combined with a DDD type pacemaker for repetitive monomorphic ventricular tachycardia. A 50-year-old man was admitted because of palpitation and near syncope attack. Electrocardiogram showed repetitive monomorphic ventricular tachycardias (RBBB LAD type) and R-R interval of about 440 msec and I degree A-V block in sinus rhythm. Electrophysiologic study disclosed that overdrive pacing in HRA suppressed ventricular tachycardias. Left ventriculography revealed a dilated left ventricular and decreased contractility. Antiarrhythmic agents such as quinidine sulfate, procainamide, disopyramide, mexiletine, lidocaine and propranolol were not effective. But, the combination of propranolol and aprindine decreased the rate of the ventricular tachycardia. With aprindine 60 mg/day and metoprolol 60 mg/day combined with the atrioventricular sequential pacing at 85/min, ventricular tachycardia completely disappeared.

A case of myasthenia gravis complicated with hyperthyroidism and thymic hyperplasia in childhood

We report here a case of myasthenia gravis complicated with hyperthyroidism and thymic hyperplasia. The patient was a 13-year-old girl with struma and hyperthyroidism which began at age 12. Two weeks following the initiation of treatment against hyperthyroidism she developed left blepharoptosis, diplopia, and dysphagia, which responded promptly to edrophonium administration. An increase of the anti-acetylcholine receptor antibody was found in the serum. A chest CT showed a large soft tissue mass in front of the ascending aorta, which was proven histopathologically as thymic hyperplasia. The patient underwent an extensive thymectomy and was placed on combination therapy with an anti-thyroid drug, glucocorticosteroid, and an anti-cholinesterase drug. Her symptoms and signs have been well controlled by this treatment. Coexistence of myasthenia gravis, hyperthyroidism, and thymic hyperplasia in childhood have never been documented in literature.

Time course and clinical significance of marked left axis deviation in airline pilots

The purpose of this study was to examine the time course and evaluate the clinical significance of marked left axis deviation (LAD) in airline pilots. The study group consisted of 30 Japan Airlines' pilots with marked LAD, identified from a group of 1,700 who are now 35 years of age or older. The mean age at examination was 48.5 +/- 5.7 years [corrected] and the mean observation period was 22.6 +/- 5.6 years [corrected]. The prevalence rate of marked LAD was 1.8%. In 20%, the axis remained unchanged, and in 70%, LAD progressed either gradually or suddenly. All subjects were examined by exercise testing and 26 had echocardiograms. Two pilots (6.7%) were found to have organic heart disease (hypertension), which was much lower than the rate reported previously. In these individuals, the onset of marked LAD was noted more than 10 years before hypertension was detected. No progression to complete left bundle branch block, nor any form of AV block, was observed among these subjects. No cardiac events or death occurred during the study period.

[Diagnostic value of the transesophageal atrial pacing stress for Tl-201 myocardial SPECT]

The stress study for Tl-201 myocardial SPECT (single photon emission computed tomography) of a patient with old myocardial infarction, who had occasionally felt a chest pain for the last 8 months was performed with the transesophageal atrial pacing. The examination was fastly started and regular pacing rates were completely obtained for every pacing rate (50-100/min). In spite of a little amount of the pacing stress, the finding of stress induced ischemia and MI were obtained on this patient. This result suggests that the transesophageal atrial pacing stress might be useful for the evaluation of ischemic heart disease by Tl-201 myocardial SPECT, and is easily applied to the old and the patient with disorder of leg movement.

AV nodal reentrant tachycardia with Mahaim fiber conduction

Paroxysmal tachycardia with widened QRS complexes was found in a 46-year-old woman. In sinus rhythm, the patient had electrocardiographic evidence of type B preexcitation with a left bundle branch block pattern. The resting PR interval (160 msec) and A-H interval (100 msec) were within normal limits, but the H-V interval (10 msec) was abnormally short. Programmed atrial extrastimuli at progressively shorter coupling intervals resulted in sudden prolongation of the A-H interval from 120 msec to 250 msec, and the His bundle activities became incorporated just after initiation of the QRS complexes. The QRS morphology was changed but the change was minimal, and atrial echo beats or sustained tachycardia with wide and preexcited QRS complexes were elicited. It is postulated that the site of reentry is within the AV node with preexcitation occurring as the result of conduction in an anomalous nodoventricular pathway.

Shift of atrial reentrant tachycardia with transient entrainment to an uncommon and a common type of atrial flutter

Atrial reentrant tachycardia (ART) which demonstrated transient entrainment shifted to an uncommon type of atrial flutter (AF) with premature atrial stimulation, and then returned to ART spontaneously. Subsequently, this ART shifted to a common type of AF by rapid atrial pacing, which was further transformed into an uncommon type of AF and finally terminated by rapid atrial pacing. The mechanism of AF in clinical cases is still controversial, but in this case, AF, both uncommon and common types, is considered due to macro-reentry within the atria. To explain the shift of ART to AF and mutual transformation between common and uncommon type of AF, we made a schematic figure of reentry loop within the atria of ART and AF.

Effects of four antiarrhythmic drugs on the induction and termination of paroxysmal supraventricular tachycardia

The electrophysiological effects of antiarrhythmic drugs were tested in 36 patients with recurrent paroxysmal supraventricular tachycardia (PSVT), 25 of whom had accessory pathway reentrant tachycardia (APRT) and 11 A-V nodal reentrant tachycardia (AVNRT; 10 of the slow-fast type one of the fast-slow type). The test drugs were procainamide (used in 19 patients), verapamil (in 27), disopyramide (in 31), and propranolol (in 15). The drugs were tested for their ability to terminate episodes of PSVT as well as to inhibit their induction. Procainamide had an inhibitory effect on APRT in nine of 12 patients (75%) and terminated episodes of APRT in seven of 11 patients (63.6%); in all of them V-A block was responsible for the termination. In four of six patients (66.7%) with slow-fast AVNRT and in one patient with fast-slow AVNRT, inhibition of the induction of tachycardia attacks was noted after procainamide. Termination of AVNRT was seen in the same number of patients. Verapamil inhibited the induction of APRT in 12 of 18 patients (66.7%) and terminated episodes of APRT in 10 of 16 patients (62.5%), all by A-V block. In six of eight patients (75%) with slow-fast AVNRT, inhibition of the induction as well as termination of tachycardia were noted after verapamil. Disopyramide had an inhibitory effect on APRT in seven of 23 patients (30.4%) and terminated APRT in five of 21 patients (23.8%) by V-A block, while AVNRT (all slow-fast type) was terminated in only one of eight patients (12.5%) by disopyramide. Disopyramide was less effective than previously reported. This could be attributed to a relatively low dosage and slow infusion speed. Propranolol inhibited the induction of APRT and terminated episodes of APRT in only one of 10 patients (10%). In two of four patients (50%) with slow-fast AVNRT, an inhibitory effect by propranolol was noted, but termination was seen in only one patients.

Utility of the filtered bipolar esophageal lead in the diagnosis of arrhythmias

Electrophysiologic study was performed in 25 patients with tachycardia or bradycardia attacks. The coronary sinus (CS) and filtered bipolar esophageal electrograms were recorded simultaneously to compare the phase of atrial activations. During sinus rhythm and high right atrial pacing, the esophageal and proximal CS atrial activations were nearly simultaneous but earlier by 26 +/- 5 msec on the average than the distal CS atrial activations. During reciprocating tachycardia due to reentry using a left-side accessory atrioventricular pathway for retrograde conduction the esophageal and CS atrial activations occurred earlier than the low septal right atrial activation, so the esophageal lead can be used as a substitute for the CS lead to clarify the eccentric retrograde atrial activation sequence. By using the filtered bipolar esophageal lead, the interval from Q wave on the surface electrocardiogram to the first rapid deflection in the esophageal atrial activation (Q-AESO interval) was measured in 15 patients with supra-ventricular tachycardia. All patients with reciprocating tachycardia due to reentry using a left side accessory atrioventricular pathway had Q-AESO intervals between 100 to 130 msec and four of five patients with a right side accessory atrioventricular pathway for retrograde conduction had Q-AESO intervals between 130 to 150 msec. In contrast, all patients with reentry in the atrioventricular node had Q-AESO intervals between 30 to 60 msec. The esophageal lead is also of value in the prompt diagnosis of atrial flutter and ventricular tachycardia, since the esophageal electrograms readily reveal the relationship between atrial and ventricular activations. In conclusion, the filtered bipolar esophageal lead provides a non-invasive method for the quick diagnosis of various arrhythmias.