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Delayed recovery of mature blood cells poses a serious, expensive, and often life-threatening problem for many stem cell transplantation recipients, particularly if heavily pretreated and serving as their own donor, or having a CB transplantation as the only therapeutic option. Importantly, the different cells required to ensure a rapid, as well as a permanent, hematopoietic recovery in these patients remain poorly defined. We now show that human CB and mobilized peripheral blood (mPB) collections contain cells that produce platelets and neutrophils within 3 weeks after being transplanted into sublethal irradiated NOD/sc/d-IL-2R7C-null mice. The cells responsible for these 2 outputs are similarly distributed between the aldehyde dehydrogenase-positive and -negative subsets of lineage marker-negative CB and mPB cells, but their overall frequencies vary independently in individual samples. In addition, their total numbers can be seen to be much (> 30-fold) lower in a single "average" CB transplantation compared with a single "average" mPB transplantation (normalized for a similar weight of the recipient), consistent with the published differential performance in adult patients of these 2 transplantation products. Experimental testing confirmed the clinical relevance of the surrogate xenotransplantation assay for quantifying cells with rapid platelet regenerative activity, underscoring its potential for future applications. [ABSTRACT FROM AUTHOR]

• Drug resistant cells (MDR) succumb to taxanes with a copolymer inhibitor of P-glycoprotein. • MDR are resensitized to taxanes using nanoparticulate formulations of drug and inhibitor. • Ultrasound enhances the accumulation of nanoparticulate (80 nm) drug and inhibitor in MDR. • Ultrasound reduces the cell viability of MDR exposed to nanoparticulate drug and inhibitor. • Ultrasound accumulates nanoparticles in cells to form depots inside the cells to overcome MDR. The objective of this study was to use ultrasound in combination with nanoparticulate formulations of taxane drugs for an additive approach to overcome multidrug resistance (MDR). Polymeric nanoparticulate formulations containing both chemotherapeutic taxane drugs and a polymeric inhibitor (MePEG 17 -b-PCL 5) of drug resistant proteins have been previously developed in an attempt to overcome MDR in cells. High frequency (>1 MHz) ultrasound has been shown to increase the uptake of cytotoxic drugs in MDR proliferating cells and has been suggested as a different way to overcome MDR, resensitize drug resistant cancer cells and allow for chemotherapeutic efficacy. MDCK-MDR cells were incubated with docetaxel (DTX) or paclitaxel (PTX) loaded, solid core, nanoparticles made from a 50:50 ratio of two diblock copolymers, MePEG 114 -b-PCL 200 and MePEG 17 -b-PCL 5 (PCL 200 /PCL 5). The accumulation of drug in MDCK-MDR cells was measured using radiolabeled drug and the viability of cells was determined using an MTS cell proliferation assay. The effect of ultrasound (4 MHz, 32 W/cm2, 10 s, 25% duty cycle) on drug uptake and cell viability was studied. Using free DTX or PTX, MDCK-MDR cells were killed at sublethal doses of drug with the P-gp inhibitor (MePEG 17 -b-PCL 5) present at a concentration of just 0.006% (m/v) and cell death began after just 3 h of incubation. Using sublethal incubation doses of PTX or DTX in PCL 200 /PCL 5 nanoparticles for 90 min, followed by a second exposure to blank PCL 200 /PCL 5 nanoparticles, cell viability dropped by approximately 60% at 24 h. Drug accumulation increased by 1.43–1.9 fold following five bursts of ultrasound applied at 90 min. Both, increased ultrasound exposure and increased concentrations of blank nanoparticles during the second incubation allowed for increased levels of cell death. The combined use of ultrasound with taxane and P-gp inhibitor loaded polymeric nanoparticles may allow for increased accumulation of drug and inhibitor which may then release both agents inside cells in a controlled manner to overcome drug resistance in MDR cells. [ABSTRACT FROM AUTHOR]

Nanoparticles composed of both high- and low-molecular-weight methoxy poly(ethylene glycol)-block-poly(caprolactone) ( Me PEG-b- PCL) diblock copolymers (termed 'mixed molecular weight nanoparticles') were investigated for the encapsulation and delivery of the taxane drugs paclitaxel ( PTX) and docetaxel ( DTX). These nanoparticles were prepared using nanoprecipitation and emulsion methods. These 80 nm nanoparticles were prepared with high yields, efficiently solubilized PTX and DTX up to 500 and 1300 μg/mL, respectively, and demonstrated controlled release of these drugs over 14 days. The taxane-sensitive ( MDCKII) and taxane-resistant [ P-glycoprotein ( P-gp) overexpressing] MDCKII- MDR cell lines were used to establish the cytotoxic profiles of these nanoparticles. Because of the coencapsulation of the previously demonstrated P-gp inhibitor, a low-molecular-weight Me PEG-b- PCL copolymer ( Me PEG17-b- PCL5), these drug-loaded mixed molecular weight nanoparticles dramatically reduced the viability of P-gp overexpressing MDCKII- MDR cells and restored sensitivity to taxane drugs in these cells. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3966-3976, 2014 [ABSTRACT FROM AUTHOR]

Much progress has been made in the management of chronic-phase chronic myeloid leukemia (CP-CML), but there is a continuing imperative to develop curative treatments, predict patient responses to specific modalities, and anticipate disease relapse or progression. These needs underlie continuing interest in methods to detect and quantify the relevant leukemic cells in clinical samples with improved reliability and specificity. We report the results of comparing three methods to enumerate primitive CP-CML cells in the same samples: genotyping CD34+38− cells directly by fluorescence in situ hybridization, and measuring BCR-ABL1 transcript-genotyped colony-forming cell outputs in either 5-week long-term cultures (LTCs) containing non-engineered mouse fibroblasts or in 6-week LTCs containing mouse fibroblasts engineered to produce human Steel factor, granulocyte colony-stimulating factor, and IL-3. The results demonstrate that the first two methods significantly overestimate the prevalence of primitive CP-CML cells by comparison to the third. In additional studies, we found that CML-CD34+ cells can repopulate the marrow and spleen of serially transplanted adult NOD/SCID-IL-2Rγ chain-null mice for more than 1 year with an almost exclusive myeloid differentiation in primary and secondary recipients and without evidence of disease progression. These findings underscore the importance of long-term functional in vitro and in vivo endpoints to identify and characterize CP-CML stem cells. [Copyright &y& Elsevier]