Pim1 Kinase Overexpression Enhances ckit+ Cardiac Stem Cell Cardiac Repair Following Myocardial Infarction in Swine.

BACKGROUND: Pim1 kinase plays an important role in cell division, survival, and commitment of precursor cells towards a myocardial lineage, and overexpression of Pim1 in ckit+ cardiac stem cells (CSCs) enhances their cardioreparative properties. OBJECTIVES: The authors sought to validate the effect of Pim1-modified CSCs in a translationally relevant large animal preclinical model of myocardial infarction (MI). METHODS: Human cardiac stem cells (hCSCs, n = 10), hckit+ CSCs overexpressing Pim1 (Pim1+; n = 9), or placebo (n = 10) were delivered by intramyocardial injection to immunosuppressed Yorkshire swine (n = 29) 2 weeks after MI. Cardiac magnetic resonance and pressure volume loops were obtained before and after cell administration. RESULTS: Whereas both hCSCs reduced MI size compared to placebo, Pim1+ cells produced a ∼3-fold greater decrease in scar mass at 8 weeks post-injection compared to hCSCs (-29.2 ± 2.7% vs. -8.4 ± 0.7%; p < 0.003). Pim1+ hCSCs also produced a 2-fold increase of viable mass compared to hCSCs at 8 weeks (113.7 ± 7.2% vs. 65.6 ± 6.8%; p <0.003), and a greater increase in regional contractility in both infarct and border zones (both p < 0.05). Both CSC types significantly increased ejection fraction at 4 weeks but this was only sustained in the Pim1+ group at 8 weeks compared to placebo. Both hCSC and Pim1+ hCSC treatment reduced afterload (p = 0.02 and p = 0.004, respectively). Mechanoenergetic recoupling was significantly greater in the Pim1+ hCSC group (p = 0.005). CONCLUSIONS: Pim1 overexpression enhanced the effect of intramyocardial delivery of CSCs to infarcted porcine hearts. These findings provide a rationale for genetic modification of stem cells and consequent translation to clinical trials.

Synergistic Effects of Combined Cell Therapy for Chronic Ischemic Cardiomyopathy.

BACKGROUND: Both bone marrow-derived mesenchymal stem cells (MSCs) and c-kit(+) cardiac stem cells (CSCs) improve left ventricular remodeling in porcine models and clinical trials. Using xenogeneic (human) cells in immunosuppressed animals with acute ischemic heart disease, we previously showed that these 2 cell types act synergistically. OBJECTIVES: To more accurately model clinical applications for heart failure, this study tested whether the combination of autologous MSCs and CSCs produce greater improvement in cardiac performance than MSCs alone in a nonimmunosuppressed porcine model of chronic ischemic cardiomyopathy. METHODS: Three months after ischemia/reperfusion injury, Göttingen swine received transendocardial injections with MSCs alone (n = 6) or in combination with cardiac-derived CSCs (n = 8), or placebo (vehicle; n = 6). Cardiac functional and anatomic parameters were assessed using cardiac magnetic resonance at baseline and before and after therapy. RESULTS: Both groups of cell-treated animals exhibited significantly reduced scar size (MSCs -44.1 ± 6.8%; CSC/MSC -37.2 ± 5.4%; placebo -12.9 ± 4.2%; p < 0.0001), increased viable tissue, and improved wall motion relative to placebo 3 months post-injection. Ejection fraction (EF) improved (MSCs 2.9 ± 1.6 EF units; CSC/MSC 6.9 ± 2.8 EF units; placebo 2.5 ± 1.6 EF units; p = 0.0009), as did stroke volume, cardiac output, and diastolic strain only in the combination-treated animals, which also exhibited increased cardiomyocyte mitotic activity. CONCLUSIONS: These findings illustrate that interactions between MSCs and CSCs enhance cardiac performance more than MSCs alone, establish the safety of autologous cell combination strategies, and support the development of second-generation cell therapeutic products.

Growth hormone-releasing hormone agonists reduce myocardial infarct scar in swine with subacute ischemic cardiomyopathy.

BACKGROUND: Growth hormone-releasing hormone agonists (GHRH-As) stimulate cardiac repair following myocardial infarction (MI) in rats through the activation of the GHRH signaling pathway within the heart. We tested the hypothesis that the administration of GHRH-As prevents ventricular remodeling in a swine subacute MI model. METHODS AND RESULTS: Twelve female Yorkshire swine (25 to 30 kg) underwent transient occlusion of the left anterior descending coronary artery (MI). Two weeks post MI, swine were randomized to receive injections of either 30 µg/kg GHRH-A (MR-409) (GHRH-A group; n=6) or vehicle (placebo group; n=6). Cardiac magnetic resonance imaging and pressure-volume loops were obtained at multiple time points. Infarct, border, and remote (noninfarcted) zones were assessed for GHRH receptor by immunohistochemistry. Four weeks of GHRH-A treatment resulted in reduced scar mass (GHRH-A: -21.9 ± 6.42%; P=0.02; placebo: 10.9 ± 5.88%; P=0.25; 2-way ANOVA; P=0.003), and scar size (percentage of left ventricular mass) (GHRH-A: -38.38 ± 4.63; P=0.0002; placebo: -14.56 ± 6.92; P=0.16; 2-way ANOVA; P=0.02). This was accompanied by improved diastolic strain. Unlike in rats, this reduced infarct size in swine was not accompanied by improved cardiac function as measured by serial hemodynamic pressure-volume analysis. GHRH receptors were abundant in cardiac tissue, with a greater density in the border zone of the GHRH-A group compared with the placebo group. CONCLUSIONS: Daily subcutaneous administration of GHRH-A is feasible and safe in a large animal model of subacute ischemic cardiomyopathy. Furthermore, GHRH-A therapy significantly reduced infarct size and improved diastolic strain, suggesting a local activation of the GHRH pathway leading to the reparative process.

Brief formalin fixation and rapid tissue processing do not affect the sensitivity of ER immunohistochemistry of breast core biopsies.

OBJECTIVES: Recent studies have questioned the supporting evidence for the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines of the 8-hour minimum fixation time required for estrogen receptor immunohistochemistry (ER-IHC) assays in breast cancer. METHODS: We investigated whether brief formalin fixation together with rapid tissue processing affects the sensitivity of ER in core breast biopsies. Five core samples each from 22 mastectomy specimens were collected and fixed in 10% formalin for periods ranging from 30 minutes to 1 week. Core 5 was fixed and processed according to the ASCO/CAP guidelines. ER-IHC was performed following heat-induced antigen retrieval using antibody 1D5. The proportion and intensity of reaction was recorded using the Q score. RESULTS: Five of 22 cancers were ER negative in all cores. In 17 ER-positive cases, no differences were found in the intensity of reaction between 30 minutes and 1 week of formalin fixation. Similarly, no difference was observed in the Q scores of rapidly and conventionally processed control tumor cores. CONCLUSIONS: Brief formalin fixation along with rapid processing has no negative effect on the sensitivity of ER-IHC in breast core biopsies. This combination significantly reduces the turnaround time for preparing breast needle biopsy specimens.

Enhanced effect of combining human cardiac stem cells and bone marrow mesenchymal stem cells to reduce infarct size and to restore cardiac function after myocardial infarction.

BACKGROUND: Because mesenchymal stem cells (MSCs) induce proliferation and differentiation of c-kit(+) cardiac stem cells (CSCs) in vivo and in vitro, we hypothesized that combining human (h) MSCs with c-kit(+) hCSCs produces greater infarct size reduction compared with either cell administered alone after myocardial infarction (MI). METHODS AND RESULTS: Yorkshire swine underwent balloon occlusion of the left anterior descending coronary artery followed by reperfusion and were immunosuppressed after MI with cyclosporine and methylprednisolone. Intramyocardial combination hCSCs/hMSCs (1 million cells/200 million cells, n=5), hCSCs alone (1 million cells, n=5), hMSCs alone (200 million cells, n=5), or placebo (phosphate-buffered saline; n=5) was injected into the infarct border zones at 14 days after MI. Phenotypic response to cell therapy was assessed by cardiac magnetic resonance imaging and micromanometer conductance catheterization hemodynamics. Although each cell therapy group had reduced MI size relative to placebo (P<0.05), the MI size reduction was 2-fold greater in combination versus either cell therapy alone (P<0.05). Accompanying enhanced MI size reduction were substantial improvement in left ventricular chamber compliance (end-diastolic pressure-volume relationship; P<0.01) and contractility (preload recruitable stroke work and dP/dtmax; P<0.05) in combination-treated swine. Ejection fraction was restored to baseline in cell-treated pigs, whereas placebo pigs had persistently depressed left ventricular function (P<0.05). Immunohistochemistry showed 7-fold enhanced engraftment of stem cells in the combination therapy group versus either cell type alone (P<0.001). CONCLUSIONS: Combining hMSCs and hCSCs as a cell therapeutic enhances scar size reduction and restores diastolic and systolic function toward normal after MI. Taken together, these findings illustrate important biological interactions between c-kit(+) CSCs and MSCs that enhance cell-based therapeutic responses.

FGF23 induces left ventricular hypertrophy.

Chronic kidney disease (CKD) is a public health epidemic that increases risk of death due to cardiovascular disease. Left ventricular hypertrophy (LVH) is an important mechanism of cardiovascular disease in individuals with CKD. Elevated levels of FGF23 have been linked to greater risks of LVH and mortality in patients with CKD, but whether these risks represent causal effects of FGF23 is unknown. Here, we report that elevated FGF23 levels are independently associated with LVH in a large, racially diverse CKD cohort. FGF23 caused pathological hypertrophy of isolated rat cardiomyocytes via FGF receptor-dependent activation of the calcineurin-NFAT signaling pathway, but this effect was independent of klotho, the coreceptor for FGF23 in the kidney and parathyroid glands. Intramyocardial or intravenous injection of FGF23 in wild-type mice resulted in LVH, and klotho-deficient mice demonstrated elevated FGF23 levels and LVH. In an established animal model of CKD, treatment with an FGF-receptor blocker attenuated LVH, although no change in blood pressure was observed. These results unveil a klotho-independent, causal role for FGF23 in the pathogenesis of LVH and suggest that chronically elevated FGF23 levels contribute directly to high rates of LVH and mortality in individuals with CKD.

Late onset sporadic dilated cardiomyopathy caused by a cardiac troponin T mutation.

Mutations in TNNT2, encoding cardiac troponin T, commonly shows early onset, aggressive dilated cardiomyopathy (DCM). This observation may influence the decision of whether to undertake clinical genetic testing for TNNT2 in later onset DCM. Further, the trigger for late onset DCM remains enigmatic. A 70-year-old woman, previously healthy with a left ventricular ejection fraction of 50%-55% at age 69, presented with DCM of unknown cause and a 4-month history progressive heart failure requiring cardiac transplantation. Clinical genetic testing revealed a novel TNNT2 R139H mutation but no relevant variants in 18 other DCM genes. Her explanted heart showed partial fatty replacement in the right ventricle. Sequencing for five arrhythmogenic right ventricular dysplasia genes was negative. Functional studies in porcine cardiac skinned fibers reconstituted with the mutant R139H troponin T protein showed decreased Ca(2+) sensitivity at pH 7, characteristic of DCM. Because fatty infiltration may acidify the myocellular environment, maximal force development examined at pH 6.5 was diminished, suggesting a possible environmental trigger. We conclude that the TNNT2 R139H mutation was likely to be disease causing. Further, later age of onset may not be relevant to exclude genetic testing for TNNT2 mutations.

Rapid-response, molecular-friendly surgical pathology: a radical departure from the century-old routine practice.

BACKGROUND: Currently, surgeons have to wait for at least 1 day to receive the pathology report of a biopsy or other surgical excision. This delay is mandated by the overnight tissue-processing methods that have been in use for more than a century. Patient anxiety and delay in treatment are consequences of this practice. Here we report the impact of a tissue-processing system on the turnaround time of surgical pathology reporting and its potential effect on overall patient management. This technique provides the feasibility for performing molecular assays on the same sample used for pathologic diagnosis. STUDY DESIGN: Biopsies and other surgically removed specimens from patients treated at the University of Miami, Jackson Memorial Hospital during calendar year 2005 were processed by an automated, microwave-assisted rapid tissue-processing method. Turnaround time for surgical pathology reports was calculated and compared with that of year 1996, the last year before the new technology was phased in. RESULTS: Total tissue-processing time was reduced from 8 to 10 hours to 67 minutes, resulting in the availability of slides in less than 3 hours. In 80% of the patients, diagnoses were reported on the same day they were received in the laboratory. The 1-day turnaround for the reports in 1996 was < 1%. Histology of rapidly processed tissues and their histochemical and immunohistochemical properties were comparable with those of the traditionally prepared material. CONCLUSIONS: The rapid turnaround capability of the new tissue-processing system has allowed the pathology laboratory to render the final report in the majority of specimens on the day they are received. The feasibility of preserving macromolecules in the same clinical samples used for diagnosis is a timely advantage in the era of molecular medicine.

Preservation of biomolecules in breast cancer tissue by a formalin-free histology system.

BACKGROUND: The potential problems associated with the use of formalin in histology, such as health hazards, degradation of RNA and cross-linking of proteins are well recognized. We describe the utilization of a formalin-free fixation and processing system for tissue detection of two important biopredictors in breast cancer - estrogen receptor and HER2 - at the RNA and protein levels. METHODS: Parallel sections of 62 cases of breast cancer were fixed in an alcohol-based molecular fixative and in formalin. Molecular fixative samples were processed by a novel formalin-free microwave-assisted processing system that preserves DNA, RNA and proteins. Formalin-fixed samples were processed using the conventional method. Estrogen receptor was assessed by immunohistochemistry and real-time PCR. HER2 was assessed by immunohistochemistry, FISH, CISH and real-time PCR. RESULTS: The immunohistochemical reaction for estrogen receptor was similar in molecular- and formalin-fixed samples (Spearman Rank R = 0.83, p < 0.05). Also HER2 result was similar to that of formalin-fixed counterparts after elimination of antigen retrieval step (Spearman Rank R = 0.84, p < 0.05). The result of HER2 amplification by FISH and CISH was identical in the molecular fixative and formalin-fixed samples; although a shorter digestion step was required when using the former fixative. Real-time PCR for both estrogen receptor and HER2 were successful in all of the molecular fixative specimens. CONCLUSION: The formalin-free tissue fixation and processing system is a practical platform for evaluation of biomolecular markers in breast cancer and it allows reliable DNA and RNA and protein studies.

Methodology for preservation of high molecular-weight RNA in paraffin-embedded tissue: application for laser-capture microdissection.

Laser-capture microdissection techniques have enhanced the ability to perform molecular studies of pure-cell populations. Although many technical factors affect the outcome of the procedure, none is more critical than the appropriate handling of the tissue. Because extraction of intact RNA from paraffin-embedded tissue is a difficult and inconsistent process, frozen sections with their attendant problems are used for this purpose. The major limitation of frozen section is its inferior morphologic quality compared with paraffin-embedded sections that may complicate accurate identification of cells during microdissection. We have developed a procedure that provides both high-quality histomorphology and RNA preservation in paraffin-embedded tissue. It is based on the use of a methanol-based fixative coupled with microwave-assisted rapid tissue processing. This technology in conjunction with a modified hematoxylin-eosin stain and a RNA extraction method allows isolation of high molecular-weight RNA from laser-capture microdissected, hematoxylin and eosin-stained paraffin sections. The high quality of the extracted RNA was confirmed by capillary electrophoresis and RT-PCR. The combination of a methanol-based fixative, rapid microwave tissue processing, and a modified hematoxylin and eosin stain produces paraffin sections that yield high molecular-weight RNA upon microdissection. This methodology opens the door for a wide range of gene expression analyses using paraffin-embedded tissue.

Immunohistochemistry of estrogen and progesterone receptors reconsidered: experience with 5,993 breast cancers.

Paraffin sections or fine-needle aspiration smears from 5,993 cases of invasive mammary carcinomas were assessed immunohistochemically for estrogen receptor (ER; 1D5) and progesterone receptor (PR; 636) expression. Staining pattern and intensity were correlated with histologic subtypes and nuclear grades of tumors. Positive nuclear staining for ER and PR was observed in 75% and 55% of invasive carcinomas, respectively. In 92% of ER+ cases, diffuse and uniform staining of most tumor cells was observed. In the remaining 8%, a focal ER reaction was seen, usually because of inadequate fixation. In 21% of PR+ tumors, the reaction was heterogeneous or focal but unrelated to fixation. There were no ER-, PR+ tumors. All pure tubular, colloid, and infiltrating lobular carcinomas were ER+. All medullary, apocrine, and metaplastic and most high-nuclear-grade carcinomas were ER-. With monoclonal antibody 1D5 and antigen retrieval, immunohistochemical reaction for ER in breast cancer usually is an all-or-none phenomenon; therefore, quantitation of results is unnecessary. Despite antigen retrieval, inadequate fixation can cause false-negative results; evaluation of internal positive control samples is imperative. ER positivity and negativity are predictable in certain histologic types and nuclear grades of breast cancer. The reaction for PR can be heterogeneous or focal.

Experience with an automated microwave-assisted rapid tissue processing method: validation of histologic quality and impact on the timeliness of diagnostic surgical pathology.

We studied the effect of a fully automated microwave-assisted rapid tissue processor (RTP) on histologic examination and on the turnaround time for surgical pathology reports. A quality assurance program reviewed the histologic sections obtained by the rapid processing method for the last 3 calendar years. In addition, the histologic results from this method were compared blindly with those obtained from the conventional overnight tissue processing (CTP) method by 9 pathologists with different levels of experience. The surgical pathology turnaround times for 1 year of use of the RTP were compared with the last year for CTP. We found that the RTP reproducibly yielded histologic material comparable in quality to CTP. The turnaround time for surgical pathology reports was improved substantially, and, in particular, same-day reporting was achieved in approximately 55% of cases compared with fewer than 1% before use of the RTP. Moreover, use of the RTP enhanced safety by eliminating formalin and xylene from the procedure.

A tissue fixative that protects macromolecules (DNA, RNA, and protein) and histomorphology in clinical samples.

Preservation of macromolecules (DNA, RNA, and proteins) in tissue is traditionally achieved by immediate freezing of the sample. Although isolation of PCR-able RNA has been reported from formalin-fixed, paraffin-embedded tissues, the process has not been shown to be reproducible because high molecular weight RNA is usually degraded. We investigated the potential value of a new universal molecular fixative (UMFIX, Sakura Finetek USA, Inc., Torrance, California) in preservation of macromolecules in paraffin-embedded tissue. Mouse and human tissues were fixed in UMFIX from 1 hour to 8 weeks. They were then processed by a rapid tissue processing (RTP) system, embedded in paraffin, and evaluated for routine histology as well as for the quality and quantity of DNA, RNA, and proteins. Formalin-fixed tissues were processed by RTP and evaluated in a similar manner. Fresh-frozen samples were used as controls. The morphology of UMFIX-exposed tissue was comparable to that fixed in formalin. High molecular weight RNA was preserved in tissue that was immediately fixed in UMFIX and stored from 1 hour to 8 weeks at room temperature. There were no significant differences between UMFIX-exposed and frozen tissues on PCR, RT-PCR, real-time PCR, and expression microarrays. Similarly, physical and antigenic preservation of proteins in UMFIX tissue was similar to fresh state. Both RNA and proteins were substantially degraded in formalin-fixed and similarly processed specimens. We concluded that it is now possible to preserve histomorphology and intact macromolecules in the same archival paraffin-embedded tissue through the use of a novel fixative and a rapid processing system.

Continuous-specimen-flow, high-throughput, 1-hour tissue processing. A system for rapid diagnostic tissue preparation.

CONTEXT: Current conventional tissue-processing methods employ fixation of tissues with neutral buffered formalin, dehydration with alcohol, and clearing with xylene before paraffin impregnation. Because the time required for this procedure is usually 8 hours or longer, it is customary to process tissues in automated instruments throughout the night. Although this time-honored method continues to serve histology laboratories well, it has a number of shortcomings, such as a 1-day delay of diagnosis, the need to batch specimens, the relatively large volumes and toxicity of reagents used, and the extent of RNA degradation. OBJECTIVE: To describe a rapid new method of tissue processing using a continuous-throughput technique. Design.-We used a combination of common histologic reagents, excluding formalin and xylene, as well as microwave energy, to develop a rapid processing method. The effect of this method on the quality of histomorphology, histochemistry, immunohistochemistry, and RNA content of processed tissue was compared with that of adjacent tissue sections processed by the conventional processing technique. We also assessed the impact of this rapid processing system on our practice by comparing the turnaround times of surgical pathology reports before and after its implementation. RESULTS: The new processing method permitted preparation of paraffin blocks from fresh or prefixed tissue in about 1 hour. The procedure allowed continuous flow of specimens at 15-minute intervals. It eliminated the use of formalin and xylene in the processing and used considerably lower volumes of other chemical reagents. Histomorphologic, histochemical, and immunohistochemical results were comparable to the parallel sections prepared by the conventional method. The new technique, however, preserved higher quality RNA. Use of the new methodology led to the diagnosis and reporting of more than one third of surgical pathology specimens on the same day that they were received, as compared to 1% of same-day reporting before the implementation of the rapid processing system. CONCLUSION: The quality of hematoxylin-eosin, histochemical, and immunohistochemical tissue sections provided by the new system is comparable to that obtained following the conventional processing method. The new system preserves RNA better than the conventional method. It also shortens the processing time to about 1 hour from the receipt of fresh or prefixed tissue, eliminates the need for formalin and xylene, and reduces the volume of other chemicals. Most importantly, it impacts overall patient management by allowing for considerably shorter turnaround times for completion of surgical pathology reports.