Scaffolds for tissue engineering of cardiac valves.

Tissue engineered heart valves offer a promising alternative for the replacement of diseased heart valves avoiding the limitations faced with currently available bioprosthetic and mechanical heart valves. In the paradigm of tissue engineering, a three-dimensional platform - the so-called scaffold - is essential for cell proliferation, growth and differentiation, as well as the ultimate generation of a functional tissue. A foundation for success in heart valve tissue engineering is a recapitulation of the complex design and diverse mechanical properties of a native valve. This article reviews technological details of the scaffolds that have been applied to date in heart valve tissue engineering research.

Utility of mesenchymal stromal cells for myocardial infarction. Transitioning from bench to bedside.

Amongst experimental therapies being evaluated for myocardial infarction (MI), the field of cellular cardiomyoplasty still provokes much excitement, well into its second decade of investigation. Mesenchymal stromal/stem cells (MSCs) have held a particularly enduring place as one of the mainstays of adult-derived stem cell research in cardiovascular disease. These rare, non-hematopoietic cells are natively present throughout different postnatal tissues, most famously bone marrow, where they typically participate in perivascular stem cell niches and play key supportive and trophic roles. Their application for exogenous stem cell delivery is made attractive by their ease of isolation, proclivity for ex vivo expansion and potential for allogeneic use. There is now a remarkable wealth of in vitro and animal-based evidence attesting to the ability of MSCs to safely augment cardiac repair post-MI through pleiotropic mechanisms that continue to be delineated and in turn, optimised. However, despite such preclinical promise and the encouraging results of preliminary experience in human patients, the broader translation of MSCs to the clinical cardiovascular realm requires much more refinement to overcome fundamental limitations, not to mention rigorous validation to resolve lingering areas of uncertainty. Here we review the basic biological properties that have made MSCs so widely investigated for cardiovascular repair, discuss the preclinical evidence for their efficacy and purported mechanisms of action and consider the practicalities and evidence for their use in human patients with MI and cardiomyopathy.

Extended survival in advanced and refractory multiple myeloma after single-agent thalidomide: identification of prognostic factors in a phase 2 study of 169 patients.

This report of a phase 2 trial of thalidomide (THAL) (200 mg/d; 200 mg increment every 2 weeks to 800 mg) for 169 patients with advanced myeloma (MM) (abnormal cytogenetics (CG), 67%; prior autotransplant, 76%) extends earlier results in 84 patients. A 25% myeloma protein reduction was obtained in 37% of patients (50% reduction in 30% of patients; near-complete or complete remission in 14%) and was more frequent with low plasma cell labeling index (PCLI) (below 0.5%) and normal CG. Two-year event-free and overall survival rates were 20% +/- 6% and 48% +/- 6%, respectively, and these were superior with normal CG, PCLI of less than 0.5%, and beta(2)-microglobulin of 3 mg/L. Response rates were higher and survival was longer especially in high-risk patients given more than 42 g THAL in 3 months (median cumulative dose) (landmark analysis); this supports a THAL dose-response effect in advanced MM.

Preceding chemotherapy, tumour load and age influence engraftment in multiple myeloma patients mobilized with granulocyte colony-stimulating factor alone.

Haematopoietic growth factors, especially granulocyte colony-stimulating factor (G-CSF), are frequently utilized alone for peripheral blood stem cell (PBSC) procurement to avoid the morbidity associated with high-dose chemotherapy (HDT). Moreover, the cytotoxic agents used may not be the most optimal therapy for the malignancy. It also makes scheduling of apheresis easier. Factors having an impact on PBSC procurement and engraftment after HDT were analysed in 117 multiple myeloma patients mobilized with G-CSF (10-16 microg/kg, median 12 microg/kg) alone using Cox regression analysis. A median of 6.2 x 10(6) CD34 cells/kg (range 0.6-34.1) were procured during leukapheresis and a median of 2.5 x 10(6) CD34 cells was infused after the first HDT (range 0.3-23.9). The only factor significantly affecting optimal PBSC procurement was duration of preceding conventional chemotherapy (P = 0.002). Granulocyte recovery was prompt in almost all patients, 75% of whom attained a granulocyte count of 0.5 x 10(9)/l by day 13 (median 11, range 7-19). However, platelet recovery to both 20 x 10(9)/l (median 12 d, range 8-50+) and 50 x 10(9)/l (median 20 d, range 7-205+) varied widely. On univariate analysis, factors influencing platelet recovery were the number of CD34 cells/kg infused, age, beta(2)-microglobulin levels, response to preceding therapy, bone marrow plasmacytosis and duration of prior therapy. Factors attaining significance on multivariate analysis included number of CD34 cells/kg infused (P = 0.007), beta(2)-microglobulin levels (P = 0.0001), most probably representing disease load, and age (P = 0.002). Patients with high tumour burden, i.e. beta(2)-microglobulin levels > 2.5 mg/l, probably benefit from chemotherapy for mobilization both in terms of cytoreduction and adequate stem cell mobilization resulting in accelerated engraftment.

Results of high-dose therapy for 1000 patients with multiple myeloma: durable complete remissions and superior survival in the absence of chromosome 13 abnormalities.

High-dose therapy (HDT) has increased complete remission (CR) rates and survival in multiple myeloma (MM). We now report on continuous CR (CCR) and associated prognostic factors in 1000 consecutive patients receiving melphalan-based tandem HDT. Five-year CCR was 52% among 112 CR patients without chromosome 13 (triangle up13) abnormalities and with beta-2-microglobulin

Melphalan plus total body irradiation (MEL-TBI) or cyclophosphamide (MEL-CY) as a conditioning regimen with second autotransplant in responding patients with myeloma is inferior compared to historical controls receiving tandem transplants with melphalan alone.

The role of more intense conditioning for second transplant was evaluated in myeloma patients achieving at least partial remission (PR) after first transplant with melphalan at 200 mg/m2. Forty-three patients received more intensive conditioning for the second transplant. Nineteen patients received cyclophosphamide 120 mg/kg along with melphalan 200 g/m2 (MEL-CY; group 1) while 24 patients received total body irradiation (1125 cGy) in conjunction with melphalan 140 mg/m2 (MEL-TBI; group 2). Forty-three matched control patients were identified from 450 patients receiving melphalan alone for second transplant (MEL200; group 3). Engraftment and toxicities were comparable among the groups with the exception of increased treatment-related mortality of 8% in group 2 compared to none in groups 1 and 3 (P = 0.07). Despite identical CR rates of 74, 71 and 70%, respectively, in groups 1, 2 and 3 (P = 1.0), event-free survival (median: 27, 15 and 61; P < 0.0001) and overall survival (median: 39, 25 and 76 months; P = 0.003) were significantly decreased in patients receiving more intensive conditioning (groups 1 and 2). Lymphocyte recovery, evaluated as a surrogate for immune recovery, was inferior in more intensively treated patients (groups 1 and 2 compared to group 3). Our findings suggest that more intense conditioning appears to have no benefit in patients responding to their first cycle of high-dose therapy and may even be detrimental in this setting. Bone Marrow Transplantation (2000) 25, 483-487.

Collection of peripheral blood stem cells after a preceding autograft: unfavorable effect of prior interferon-alpha therapy.

Eighty-eight previously autografted (78 transplanted twice and 10 once) myeloma patients who had no cryopreserved stem cells available for possible future use received G-CSF for mobilization of stem cells. One-fourth of the patients had progressive disease at the time of apheresis. All patients had received 200 mg/m2 melphalan for the first transplant. The interval between the preceding transplant and the harvest was 5-68 months (median 29). A total of 0.46-9.16 (median 3.03) x 10(6) CD34+ cells/kg were collected. More than 2 x 10(6)/kg CD34+ cells were collected in 76% of the patients, and > or = 5 x 10(6)/kg in 14%. On multivariate analysis, patients with platelet counts of > or = 200 x 10(9)/l (P < 0.0001), those who had not received any myelosuppressive chemotherapy between the last transplant and the collection (P = 0.02), and those who had received interferon-alpha for < or = 6 months (P = 0.03) had better collections. Eleven of 12 patients autografted with these cells had prompt neutrophil recovery (median 10 days to 0.5 x 10(9)/l) but recovery to 50 x 10(9)/l platelets was delayed or incomplete in 11 of 12. We conclude that it is possible to harvest peripheral blood stem cells with G-CSF stimulation in patients who have been autografted previously. Limited data suggest that platelet recovery may be suboptimal when these cells are used. These findings have practical implications for patients with malignant diseases in remission after autografting who may be candidates for future salvage therapy but have no stem cells stored, and for patients with chronic myeloid leukemia who are on long-term interferon-alpha therapy to attain cytogenetic remission for eventual collection of normal stem cells.

Age is not a prognostic variable with autotransplants for multiple myeloma.

Multiple myeloma (MM) typically afflicts elderly patients with a median age of 65 years. However, while recently shown to provide superior outcome to standard treatment, high-dose therapy (HDT) has usually been limited to patients up to 65 years. Among 550 patients with MM and a minimum follow-up of 18 months, 49 aged >/=65 years were identified (median age, 67; range, 65 to 76 years). Their outcome was compared with 49 younger pair mates (median, 52; range, 37 to 64 years) selected among the remaining 501 younger patients (<65 years) matched for five previously recognized critical prognostic factors (cytogenetics, beta2-microglobulin, C-reactive protein, albumin, creatinine). Nearly one half had been treated for more than 1 year with standard therapy and about one third had refractory MM. All patients received high-dose melphalan-based therapy; 76% of the younger and 65% of the older group completed a second transplant (P =.3). Sufficient peripheral blood stem cells to support two HDT cycles (CD34 > 5 x 10(6)/kg) were available in 83% of younger and 73% of older patients (P =.2). After HDT, hematopoietic recovery to critical levels of granulocytes (>500/microL) and of platelets (>50,000/microL) proceeded at comparable rates among younger and older subjects with both first and second HDT. The frequency of extramedullary toxicities was comparable. Treatment-related mortality with the first HDT cycle was 2% in younger and 8% among older subjects, whereas no mortality was encountered with the second transplant procedure. Comparing younger/older subjects, median durations of event-free and overall survival were 2.8/1.5 years (P =.2) and 4.8/3.3 years (P =.4). Multivariate analysis showed pretransplant cytogenetics and beta2-microglobulin levels as critical prognostic features for both event-free and overall survival, whereas age was insignificant for both endpoints (P =.2/.8). Thus, age is not a biologically adverse parameter for patients with MM receiving high-dose melphalan-based therapy with peripheral blood stem cell support and, hence, should not constitute an exclusion criterion for participation in what appears to be superior therapy for symptomatic MM.

Total therapy with tandem transplants for newly diagnosed multiple myeloma.

Between August 1990 and August 1995, 231 patients (median age 51, 53% Durie-Salmon stage III, median serum beta-2-microglobulin 3.1 g/L, median C-reactive protein 4 g/L) with symptomatic multiple myeloma were enrolled in a program that used a series of induction regimens and two cycles of high-dose therapy ("Total Therapy"). Remission induction utilized non-cross-resistant regimens (vincristine-doxorubicin-dexamethasone [VAD], high-dose cyclophosphamide and granulocyte-macrophage colony-stimulating factor with peripheral blood stem cell collection, and etoposide-dexamethasone-cytarabine-cisplatin). The first high-dose treatment comprised melphalan 200 mg/m2 and was repeated if complete (CR) or partial (PR) remission was maintained after the first transplant; in case of less than PR, total body irradiation or cyclophosphamide was added. Interferon--2b maintenance was used after the second autotransplant. Fourteen patients with HLA-compatible donors underwent an allograft as their second high-dose therapy cycle. Eighty-eight percent completed induction therapy whereas first and second transplants were performed in 84% and 71% (the majority within 8 and 15 months, respectively). Eight patients (3%) died of toxicity during induction, and 2 (1%) and 6 (4%) during the two transplants. True CR and at least a PR (PR plus CR) were obtained in 5% (34%) after VAD, 15% (65%) at the end of induction, and 26% (75%) after the first and 41% (83%) after the second transplants (intent-to-treat). Median overall (OS) and event-free (EFS) survival durations were 68 and 43 months, respectively. Actuarial 5-year OS and EFS rates were 58% and 42%, respectively. The median time to disease progression or relapse was 52 months. Among the 94 patients achieving CR, the median CR duration was 50 months. On multivariate analysis, superior EFS and OS were observed in the absence of unfavorable karyotypes (11q breakpoint abnormalities, -13 or 13-q) and with low beta-2-microglobulin at diagnosis. CR duration was significantly longer with early onset of CR and favorable karyotypes. Time-dependent covariate analysis suggested that timely application of a second transplant extended both EFS and OS significantly, independent of cytogenetics and beta-2-microglobulin. Total Therapy represents a comprehensive treatment approach for newly diagnosed myeloma patients, using multi-regimen induction and tandem transplantation followed by interferon maintenance. As a result, the proportion of patients attaining CR increased progressively with continuing therapy. This observation is particularly important because CR is a sine qua non for long-term disease control and, eventually, cure.

The effects of gastric hyperosmotic glucose feedings on regional perfusion in the neonatal piglet.

Regional blood flow and intestinal wall perfusion were studied in 13 anesthetized 1-5 day old neonatal piglets before and after gastric glucose infusion. The radionuclide labeled microsphere technique was used with 15 +/- 3 mu microspheres (85Sr, 141Ce) given in two separate left atrial infections. The 10% glucose with a patent blue dye marker did not affect CO but produced significant increases in blood flow to the adrenals bilaterally, to all layers of the proximal small intestine and to the mucosa of the distal small intestine. The glucose also caused a significant reduction in the animals' arterial pH, PaO2, and total CO2 with an increase in the blood glucose level. This response to gastric glucose infusion is different from adult animals since lower glucose concentrations produced blood flow changes in all layers of the exposed small intestine and the adrenals in our neonatal animals.

Poly(ethylene oxide), a new slowing agent for protozoa.

The water-soluble, viscoelastic resin Polyox WSR 301), a poly(ethylene oxide) of high molecular weight (approximately 4 million) is introduces as a new slowing agent for protozoa. Generally, as the kinetic viscosity of the resin increased from 0.25% to 1% (w/v), the swimming velocity of Euglena gracilis, Didnium nasutum, Paramecium aurelia, Blepharisma undulans, and Prorodon platyodon decreased. The 1.0% solution had the highest viscosity and decreased velocity more effectively than 1.0% methyl cellulose and Protoslo solutions. The Polyox solutions differed from those of methyl cellulose and Protoslo by having, in addition to viscous drag, an elastic recoil that pulled the protozoa backwards when their swimming efforts stopped. The toxicity of these slowing agents was determined using 10 P. aurelia/test slide preparation. Paramecium numbers decreased in 1.0% methyl cellulose and Protoslo to nearly zero by 24 hr; in Polyox, not only were most these ciliates alive after 24 hr, but many survived for 96 hr and divisions occurred in 0.25% and 0.50% solutions.

A rapid radiometric method for determining the sensitivity of clinical isolates of Mycobacterium tuberculosis to several chemotherapeutic agents.

Current methods of performing antibiotic susceptibility tests on M. tuberculosis require 4 to 6 weeks for completion and in some cases have a poor correlation with clinical results. We have developed a rapid radiometric method of sensitivity testing which utilizes the incorporation of 3H-uracil into ribonucleic acid (RNA) as a measure of mycobacterial growth. The radiometric method is sensitive and reproducible and the results are completed in 48 hours. An excellent correlation was found between the radiometric method of sensitivity testing and the traditional agar plate technique when the two were compared with respect to isoniazid, streptomycin, and rifampicin sensitivities. There was no correlation between the two methods when ethambutol was tested. These results have confirmed our previous experiments on the usefulness of the radiometric method for the rapid determination of antibiotic susceptibilities of mycobacteria.