HALO®-96 PRT

A Predictive Residual Toxicity Assay for Primitive Lympho-Hematopoietic Stem Cells

Buy HALO®-96 PRT assay kits

Available as assay kits and
contract research services.

HALO®-96 PRT Applications

• To determine the proportion of primitive lympho-hematopoietic stem cells remaining or resistant to drug administration.
• To determine whether primitive lympho-hematopoietic stem cells change their sensitivity to a drug after a single dose.
• To determine the effect on primitive stem cells of multiple drug administration.
• To determine whether primitive lympho-hematopoietic stem cells exhibit expansion potential after a single drug dose.

Advantages of using HALO-96 PRT to Detect Residual Stem Cell Toxicity

• Cheaper and more efficient than animal testing (3Rs) and can be applied directly to fresh, primary human cells.
• The only in vitro assay available that can detect whether primitive stem cells are available for potentially repopulating the lympho-hematopoietic system after a single drug dose.
• The only assay available that indicates changes in drug sensitivity to primitive stem cells.
• Uses a 2-stage primitive stem cell "priming" and cell expansion in vitro re-plating technology.
• Incorporates Suspension Expansion Culture (SEC) and proven Bioluminomics™ Technology.
• Designed for multiplexing with other assays, including flow cytometry and gene expression analysis, to obtain the most information from a single sample.

Species

• Human
• Non-human primate
• Dog
• Rat
• Mouse
• as well as horse, pig and sheep.

Tissues

HALO®-96 PRT is only for use with bone marrow from the above species.

Cell Populations Tested

HALO®-96 PRT is only used for the primitive lympho-hematopoietic stem cell populations:

• HPP-SP 1
• HPP-SP 2

Use

For Research Use Only.

Major Equipment Required

Plate luminometer or multiparameter plate reader with "glow" luminescence measuring capability.

Kit Contents

• HALO®-96 PRT Master Mix
• ATP standard
• ATP high and low controls
• ATP Enumeration Reagent
• 2 or 4 sterile, 96-well plates
• Non-sterile, 96-well plates
• Sterile, adhesive foil covers
• Instruction manual

Related Assays

• LumiSTEM™-96 PRT
• HALO®-Tox HT
• LUMENESC™-Tox HT
• STEMGlo™-HT
• STEMGlo™-PRT
• XVPrime™-HT
• XVPrime™-PRT

HALO®-384 DDI

A Cell-Based Drug-Drug Interaction Assay Platform for Lympho-Hematopoietic Stem Cells

HALO®-384 DDI is only available as a contract research service.

HALO®-384 DDI Applications

• To determine the cellular effects of two or more drugs interacting with each other that might result in extreme changes to the lympho-hematopoietic system.

Advantages of using HALO®-384 DDI to Investigate Drug-Drug Interactions

• HALO®-384 DDI can detect potentially harmful drug-drug interactions to the lympho-hematopoietic system. Drug-drug interactions are usually detected by induction or inhibition of cytochrome P450 enzymes in hepatocytes of the liver. However, these enzymes are also present in the mitochondria of cells of other tissues and organs and can result in potentially serious local perturbations. 
• HALO®-384 DDI is the only cell-based in vitro drug interaction platform available for cells of the blood-forming system.
• HALO®-384 DDI can be combined with LUMENESC™-384 DDI and LumiSTEM™-384 DDI to compare drug interactions on multiple cell types and species. Please see ComparaTOX™.
• HALO®-384 DDI uses Suspension Expansion Culture (SEC) and proven Bioluminomics™ Technology to provide an advanced, powerful and reliable assay platform for toxicity testing.

Species

• Human
• Non-human primate
• Dog
• Rat
• Mouse

Tissues

All HALO®-384 DDI assays are performed on bone marrow cells. 

Examples of Drug-Drug Interactions using HALO®-384 DDI

1. Cimetidine and Warfarin

Cimetidine (Tagamet) inhibits a number of cytochrome P450 enzymes including 1A2, 2C9 and 2C19 all three of which also affect Warfarin. The results shown in the top diagrams demonstrate that when Cimetidine and Warfarin are titrated against each other, there is a gradual inhibition from 1nM to 1µM, followed by an increase in ATP concentrations at the 10µM and 100µM drug doses, indicating that the two drugs are interacting with each other at these doses and resulting in a reduction in the effect of the drugs.

2. Cyclosporine and Verapamil

The dose response curve for Cyclosporine indicates that it does not have an affect on the hematopoietic stem cell population, CFC-GEMM 1. In contrast, Verapamil is cytotoxic to this stem cell population at high doses. Both Cyclosporine and Verapamil inhibits cytochrome P450 3A4 and interact with each other. This interaction at the cellular, hematopoietic stem cell level is quite dramatic and shown in the bottom diagram. Although Cyclosporine has no effect on the hematopoietic stem cells over the dose range studied, in the presence of Verapamil, there is complete inhibition. However, at the highest dose for each drug, this inhibition is dramatically and completely overcome, producing ATP values as if no effect was seen.

Measuring the CYP450 enzyme response provides an indication that drug-drug interaction occurs, at least in the liver hepatocytes. However, it provides no information regarding the cellular effects that might be observed in different tissues. The data demonstrate that the drug-drug interactions predicted by the CYP450 system can be extended to cellular systems which, in turn, provide considerably more relevant information at the cellular level.