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Biological assay development and validation

Biological assays are experimental methods for assessing the presence, localization, or biological activity of a substance in living cells and biological matrices. Such methods are essential to biological science and technology. Many applications require novel assays to answer new questions, and existing assays must be implemented in a way that is robust and reproducible. Assay development and validation are routinely performed at SRI. Our scientists develop biological assays for application to basic science, drug discovery and development, and creation of diagnostics.

Biological assay types

Cell-based assays

Measurements made on cultured cells provide information about the chemical and physical state of the cells. These assays probe the biological effects of changing physiological conditions or added agents such as drugs or toxins. SRI researchers use cell-based assays to identify new therapeutic targets, discover new drugs, test chemicals for toxicity, detect pathogen infection, engineer cell function, and study the normal mechanisms underlying cell behavior.

SRI has extensive experience developing cell-based assays that address a wide range of biological questions and challenges:

  • Cell viability/compound cytotoxicity assays
  • Cell proliferation
  • Apoptosis
  • Autophagy
  • RNAi-based target validation
  • Intracellular pathogen assays
  • Cellular reporter assays
  • Novel fluorescence probes

 

Functional genomics and proteomics

Functional genomics is a field of biology that focuses on the expression and function of genes and their protein products. It comprises methods to study and characterize the molecular interactions that translate into structure, function, and behavior of cells and organisms. Tools to measure many products of gene expression in parallel are essential to this area of research. They include proteomics methods for characterizing complex collections of proteins.

SRI’s experience developing assays for functional genomics and proteomics includes:

  • Shotgun and quantitative approaches
  • Gene editing with CRISPR/Cas 9
  • Characterization of post-translational modifications
  • SiRNA
  • Gene expression analysis using mRNA arrays and miRNA arrays
  • Gene expression analysis using reporter genes

 

Imaging and analysis

Imaging technologies enable scientists to see biological phenomena that are invisible to the unaided human eye. Biologists at SRI apply imaging and image analysis methods to a wide range of investigations, including detecting and locating proteins within living cells and tissues, visualizing the internal structures and biochemistry of living organisms, and visualizing biological structures that are simply too small to see.

SRI’s expertise in biological imaging and image analysis includes:

  • Specialized histology
  • Immunocytochemistry
  • High content imaging
  • Confocal and Fluorescence microscopy
  • Transmission and scanning electron microscopy
  • Quantitative image analysis
  • Noninvasive fluorescence, bioluminescence, and X-ray imaging

 

Clinical laboratory analyses

SRI’s Clinical Analysis Laboratory is fully compliant with FDA Good Laboratory Practice (GLP) regulations and uses state-of-the-art instrumentation and data management to offer full capabilities for standard and specialized services for both human and veterinary clinical research samples.

Our capabilities include:

  • Broad range of routine and specialized hematology and clinical chemistry services
  • Routine and specialized analyses for coagulation and urinalysis parameters
  • Recently FDA- and EMEA-approved biomarkers of toxicity for kidney, liver, muscle, and other target organs

 

Discovery ADMET and in vitro metabolism

SRI is a leader in the development and application of in vitro models for ADMET evaluations (ADMET: Absorption, Distribution, Metabolism, Excretion, and Toxicity). Obtaining data on potential toxicity early in the development process can help you make informed decisions to move promising leads forward and exclude liabilities. Our staff has extensive experience in elucidating tissue-specific mechanisms of toxicity for various species and organs. We pioneered the application of human tissue preparations to predicting interspecies differences in drug metabolism, potential drug interactions, and human drug metabolizing enzymes.

Predictive ADMET

  • Membrane permeability: PAMPA, Caco-2, MDCK cells
  • Metabolic stability: liver or small intestine microsomes
  • Plasma stability
  • Cytochrome P450 (CYP) inhibition
  • Plasma protein binding
  • p-Glycoprotein substrate assays
  • In vivo pharmacokinetic screens
  • High-throughput LC-MS/MS quantitation
  • First in vivo dose to mice

In vitro metabolism and toxicity

  • Metabolite profiling and identification
  • Reaction phenotyping: CYP, UGT, SULT
  • Drug-drug interactions
  • Peroxisome proliferation
  • Co-incubation screens
  • Therapeutic index estimations
  • Cytotoxicity and hepatotoxicity screening
  • Mini-Ames mutagenicity screen
  • Mini I (hERG) cardiotox liability screen

 

Drug metabolism and pharmacokinetics

SRI offers comprehensive drug metabolism and pharmacokinetic (DMPK) services to meet your needs. We give you access to a complete range of capabilities, beginning with dose administration followed by full-service bioanalytical support and pharmacokinetic data analysis and interpretation. We offer PK studies that fully comply with U.S. FDA GLP regulations.

Bioanalytical quantitative methods

  • Bioanalytical method development and validation
    • Small molecules: LC/ MS/MS, GC-MS, HPLC with UV, fluorescence, radiochemical detection
    • Proteins: ELISA, antibody titer
  • Quantitative PCR
    • DNA/RNA test article, e.g., plasmid, virus
    • Biodistribution, persistence, integration
    • mRNA expression levels
    • Subcellular localization
    • Chromosomal integration

Pharmacokinetic and pharmacodynamic analyses

  • Single-dose pharmacokinetics
  • Bioavailability
  • Multiple-dose pharmacokinetics
  • Drug accumulation
  • Metabolite identification
  • WinNonlinTM compartmental and noncompartmental analysis
  • PK/PD interpretation
  • Bioequivalence
  • Allometric estimations
  • Formulation screening

Comprehensive ADME

  • Absorption and clearance
  • Tissue distribution
  • DNA/RNA biodistribution, persistence, integration
  • Interspecies comparative metabolism
  • Metabolite profile
  • Excretion and mass balance
  • Radiolabeled drug synthesis

 

Immunology services

SRI International Immunology Services Facility provides quality services in the area of immunology, virology, autoimmunity and inflammation that covers all stages of drug discovery and development. With state-of-the-art instruments, laboratory, and validated software systems, the Immunology team offers customized services to meet clients’ needs which includes but is not limited to assay development and validation for preclinical and clinical studies, as well as preclinical and clinical sample analysis.

  • Assessment of immunogenicity (flow cytometry, ELISA, and ELISPOT)
    • Cellular and humoral
    • Antidrug antibody (ADA)
    • Neutralizing antibody (NAb)
  • Measurement of large molecules in biological fluids
    • Measurement of antibodies, proteins, and peptides in biological fluids
    • Measurement of vaccine efficacy, potency and stability
    • Immunotoxicology evaluation
  • Measurement of cytokines
  • Biomarker analysis (flow cytometry and ELISA)
  • Receptor binding and cell-based assays
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