Penn Diabetes Center - Radioimmunoassay and Biomarkers Core

Overview

The Radioimmunoassay & Biomarkers Core offers a large number of high-quality immunoassay and biochemistry services to basic, translational, and clinical investigators performing diabetes, obesity and related metabolic disease research. The performance of a large number of immunoassay services in a central core facility rather than in scattered locations throughout the University provides a significant overall savings in equipment, personnel effort, and supplies that reduces costs for investigators, while importantly allowing for the generation of results with superior quality due to our enhanced quality control/quality assurance/quality management (QA/QC/QM) processes.

Location: 12th floor of the Smilow Center for Translational Research (room 12-183) near the Islet Cell Biology Core, Functional Genomics Core, Rodent Metabolic Phenotyping Core and the Metabolic Tracer Resource.

Billing: iLab, a cross-University site for sample submission.

Core Functions

Platforms: radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), multiplex ELISA on the Luminex MAGPIX platform, multiplex ELISA on the ELLA platform, metabolite assays on the Yellow Springs Instruments (YSI) platform.

Sample types: blood, urine, salivary and extracted tissue samples.

Approximately 215 different diabetes, obesity and metabolism-related biomarkers can be assayed. Samples generated for assay in the DRC Islet Cell Biology and Rodent Metabolic Phenotyping Cores are delivered directly to the RIA/Biomarker Core for analysis, ensuring proper collection, handling, reporting, and interpretation of data generated from the DRC Scientific Cores.

The DRC RIA/Biomarkers Core has an established relationship with the NIDDK-sponsored Chronic Renal Insufficiency Cohort (CRIC) Study central laboratory located on the 1st floor of the Smilow Center that provides access to Roche clinical autoanalyzer services for DRC investigators.

Services

Islet Assays: RIA services at Penn are unique to the RIA/Biomarkers Core and offer high-volume, rapid turnaround of affordably priced insulin, C-peptide, proinsulin and glucagon assays for human and rodent blood and tissue samples. RIA services are also established for measuring pancreatic polypeptide, and somatostatin. ELISA services are also available to assay insulin from low sample volume mouse studies, and for non-human primate studies to assay monkey insulin and C-peptide.

Gastrointestinal: Gastrointestinal hormones and adipokines including ghrelin, PYY, leptin, and adiponectin are routinely measured by RIA, while others such as GLP-1, GIP are routinely measured by conventional ELISA.

Multiplex ELISA: Multiplex services are available on the Luminex MAGPIX platform which measures multiple proteins simultaneously on magnetic bead based immunoassays. This technology can be particularly useful to investigators studying mouse models and those with repeated sampling human protocols, where sample volumes are often low. Cytokines are assayed on either the Luminex or ELLA platform. ELLA is a microfluidic-based multiplex ELISA Automated Immunoassay System that offers high sensitivity, multiplexed immunoassays for enhanced detection of low concentration analytes with high reproducibility.

In all cases, we use commercial kits and commercial quality control material from suppliers that focus on endocrinology research requirements (e.g. Millipore, R&D Systems, Mercodia, ALPCO, etc.). In order to minimize cost, insulin, C-peptide, proinsulin and glucagon are grouped in batches and processed within two weeks. Other hormones are processed within two weeks of kit arrival. All immunoassays and metabolite assays are run in duplicate (and for some ELLA assays in triplicate) with both intra- and inter-assay coefficients of variation (c.v.) standardly assessed as part of our QC/QA/QM processes.

Most frequently assayed hormones and biomarkers:

ISLET	GASTROINTESTINAL	COUNTER-REGULATORY	REPRODUCTIVE	ADIPO/ CYTOKINE	CLINICAL CHEM.
Insulin	GIP, total & active	ACTH	Estradiol	Leptin	Glucose/lactate
C-peptide	GLP-1, total & active	Cortisol	Progesterone	Adiponectin	β-hydroxybutyrate
Proinsulin	GLP-2	Corticosterone	Testosterone	Resistin	FFAs & glycerol
Amylin	Gastrin	Growth hormone	Prolactin	TNF-α	Triglycerides
Glucagon	Ghrelin, total & active	IGF-1	SHBG	IL-6	Total cholesterol
PP	PYY, total & active	IGF-1	FSH/LH	IL-1β	HDL-C/LDL-C
Somatostatin	DPP4 mass & activity	Epinephrine*	T4/T3	hsCRP	AST/ALT/ALK
cAMP	FGF-21	Norepinephrine*	TSH	Multiplex	BUN/creatinine

PP, pancreatic polypeptide; cAMP, cyclic adenosine monophosphate; GIP, glucose-dependent insulinotropic polypeptide; GLP, glucagon-like peptide; PYY, peptide tyrosine tyrosine; DPP4, dipeptidylpeptidase-4; FGF-21, fibroblast growth factor-21; ACTH, adrenocorticotropic hormone; CBG, corticosteroid binding globulin; IGF-1, insulin-like growth factor-1; SHBG, sex hormone binding globulin; FSH, follicle stimulating hormone; LH, luteinizing hormone; T4, thyroxine; T3, triiodothyronine; TSH, thyroid stimulating hormone; TNF, tumor necrosis factor; IL, interleukin; hsCRP, high sensitivity C-reactive protein. *Offered in collaboration with the Penn Metabolomics Core.

Consultation, Training and Education

The RIA/Biomarkers Core director, Dr. Michael Rickels, and technical director, Dr. Heather Collins, advise investigators on determining the best assay method, proper collection strategy, and the costs involved to address their scientific question. This consultation starts at the time of preparation of research grants to assist investigators with appropriately budgeting for assay costs, as well as the supplies and reagents necessary for the proper collection of samples for particular assays. In order to measure multiple analytes with small sample volumes, multiplexing of ELISAs by Luminex or ELLA is often required.

New assays are implemented as needed. Using the information discussed during the consultation, investigators will receive a quote that includes the assays, the sample volume required, the additives needed and the pricing information so that investigators can accurately budget these items when applying for grant funding. Certain additives such as protease inhibitors for protection of islet and gastrointestinal hormone peptides can be prepared by the Core for use by investigators with an additional charge.

After funding, Drs. Collins and Rickels meet with investigators, coordinators and nurses to train them on the procedures for collecting samples for reliable measurement, including the addition of chemicals and/or protease inhibitors as may be required for the protection of intact peptide hormones. Where study subjects are evaluated cross-sectionally or prospectively before and after intervention, samples are batched with representation across groups and with longitudinal samples from the same subjects assayed simultaneously to minimize inter-assay variation from affecting effect sizes.

The Core provides necessary supplies and standard operating procedures (SOPs) to investigators and their teams to ensure optimal biospecimen processing practice.

Training and Education

The RIA/Biomarkers Core is dedicated to providing outreach and training for the DRC research community in order to support the highest standard of biomarker research for diabetes, obesity and related metabolic disorders. As part of the education and training function of the core, Drs. Collins and Rickels meet with investigators, coordinators and nurses to train them on the procedures for collecting samples for reliable measurement, including the addition of chemicals and/or proteases as may be required for the protection of intact peptide hormones.

Where study subjects are evaluated cross-sectionally or prospectively before and after intervention, samples are batched with representation across groups and with longitudinal samples from the same subjects assayed simultaneously to minimize inter-assay variation from affecting effect sizes. Thus, collection and storage conditions for samples are critical and the Core provides necessary supplies and standard operating procedures (SOPs) to investigators and their teams to ensure optimal practice.

As Director of the Translational Research Program for IDOM, and Associate Director of the Penn Center for Human Phenomic Science (CHPS), Dr. Rickels supervises clinical research and nursing staff who contribute to investigator training and facilitate the implementation of appropriate sample collection and processing procedures in the CHPS units where the clinical and translational research studies in diabetes and obesity are conducted.