Download - Challenges in Mol. Bio. Pres
MPF 604INSTRUCTOR: Dr. C. Kassanga
STUDENTS: Keziah Maina MHA/E/2015/0005 Tipezenji Sakala
MHA/E/2015/0004
Challenges in Collection, Storage and Processing of Biological Samples
OutlineIntroductionSample collectionSample processingSample bankingQuality controlConclusion
Introduction Molecular epidemiology incorporates
epidemiology principles and knowledge of molecular events that lead to disease
It uses the concept of biomarkers to describe the molecular events characteristic for various stages between exposure and disease
A molecular epidemiologic study has various components
IntroductionStudy design
planning phaseDefine sample type
and biomarkers of interest
Pilot study; validate biomarkers, best conditions and factors affecting their stability
Informed consent; for current, future and unforeseen use of samples
Sample CollectionA biospecimen taken by
sampling; a representative of any other specimen taken from the source
Sourcesbody fluids e.g blood,
urineTissuesCultured cellsExfoliated cellsTissue/organ swabs
Challenges on sample collectionInteraction between
study subjects, field personnel and researchersEstablish clear
communication Deliver clear
instructions to staff and study subjects
Reinforced by written protocols and frequent communication
Methods of sample collectionInvasive vs. Non-
invasive methods
TimingMinute-to-minute/ hour-
to-hour variationMetabolic variationPre-clinical disease
Challenges on sample collectionStability of samples
Anticoagulants; some required/better or contraindicated
Stabilizing agents; for unstable biomarkers
Temperature; depend on biomarker of interest
Timing before initial processing; depend on components of interest and their stability
Sterility; esp for RNA isolation and cell culture
Endogenous degrading enzymes; proteins by proteases and RNA by RNAases.
Shipment; Specific regulations , packaging, labeling and documentation of shipped goods
Challenges on sample collectionStrict adherence to
protocolsThe larger the study,
the greater the challenge.
Produce SOPsTraining of all indiv.Ensure strict adherence
Safety; Samples are potentially
infectious personnel training on
safety precautions
Containers/equipmentFor collection,storage and
processingdepends on the sample
volume, means of transfer to the laboratory, cost, storage efficiency, and intended analyses
Paper trail; includes collection details (date,
sample number, type and volume),
shipping information (rcp’ts and tracking nos.) and
chain of custody forms
Sample processingProduces a number of
samples to be analyzed or banked for future use
Variety of processing protocols;Aliquoting and freezingBlood: clot & serumCryopreservation
Sample processing cont’ndMore effective processing, provisions for(1) isolating large quantities of DNA; (2) storing high-quality RNA; (3)using buccal cell DNA, blood clot (or blood smears)for genotyping; (4) separating lymphocyte from granulocyte DNA/RNA; (5) making metaphase spreads (useful for many years); (6) cryopreserving freshly isolated lymphocytes or whole blood to be recultured (7) preparing slides of exfoliated cells
Challenges of Sample processing Time
Some biomarkers may decay soon after collxn
Essential to process asap
On-site processing for preservation e.g aliquoting
SterilityCells for culture
processing or cryopreservation(DMSO, liquid nitrogen)
Record keepingTime schedules
and pre-made tables (# and vol.)
*large quantities
Sample Banking Biological bank or
Biorepository Goal is
Make possible for future analysis for currently unknown biomarkers
Minimizes research costs for future studies
Challenges of Sample bankingPhysical spaceLabelling & data
mg’t; effective trackingBarcodingInventory
management system;Electronic data managment systems (database)
Challenges of Sample banking cont’d
Natural disasters and Equipment failureStore duplicate
aliquotes in different physical location
Deterioration of stored specimens tested on regular
basis
Examples of biobanksEuropean Cancer
BankNational Cancer
Institute BiobankSchool of Public
Health Biorepository, University of California, Berkely
The Future of banking and biodepositories
Nanobarcoding DNA strands form barcode-like latticeNanobarcodes composed of cyclindrically-
shaped ‘stripped’ metal nano-particlesStore a lot of information on small space
CryobanksSamples stored in small plates; many samples
attached to memory chipTemperature electronics and robotics
Completely automated DNA isolation and banking
Quality ControlOverall- system application of optimal
procedures, ensure valid ,reproducible and accurate results
International Organisation of Standardization (ISO) created QMS(quality management systems) standards
International Epidemiology Association(IEA) created GEP(Good Epidemiological Practices).. Quality assurance in epidemiology studies
Quality control cont’ndQuality assurance practices include
SOPs specified for each type of biological sample(QMS-BS); collection, processing, shipping and storage
Document and sample control- ID and tracebilityPurchases and subcontracting- std. materials
usedProcess control- from beginning of study; ID of BS,
steps of collxn, processing, storage, shipment and analysis
Conclusion
Proper handling of biological samples protects quality ofspecimens and validity of results
Advances in molecular genetics can only be taken advantage of if sample quality is assured for already available and future biomarkers
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