Technical and Operational Best Practices

Biospecimen Collection, Processing, Storage, Retrieval, and Dissemination

The aim of every biospecimen resource should be to collect, maintain, and disseminate the highest quality biospecimens, based on the intended research use. High-quality biospecimens are defined as those that most closely resemble the biospecimen prior to its removal from the human research participant. Once the biospecimen is collected (and sometimes prior to its removal) the biospecimen may begin to take on new characteristics based on changes to the biospecimen's environment; e.g., changes in exposure to certain nutritional, chemical, or other environmental factors that may occur during a surgical or collection procedure. Such changes may result in inaccurate determinations of the molecular and physical characteristics of those components during subsequent analysis. Every attempt should be made to minimize the effects of biospecimen handling on biospecimen integrity.

Note that guidance provided in this section is intended to be applied when planning biospecimen collection, prior to the initiation of the collection efforts. In addition, study design will dictate whether certain variables can be controlled and data collected as described below.

B.2.1. Pre-Analytic and Analytic Variables

• B.2.1.1. Pre-Analytic Variables
  Pre-analytic variables may be divided into three general areas:
  • The physiology of the human research participant prior to biospecimen collection
  • Specimen collection practices; and
  • Specimen handling practices prior to their inclusion in downstream testing
  • B.2.1.1.1. Physiology of the Human Research Participant. Research has demonstrated that levels of analytes may be affected by a variety of factors such as the overall health of the human research participant, food and beverages consumed prior to biospecimen collection, the medication status of the patient, and the time of day at which the biospecimen is collected (Taheri et al. 2004; Rosenkranz et al. 2007) . Additional factors, such as phase of the menstrual cycle in females, may affect some downstream analyses. Efforts should be made to collect and record information pertaining to these variables to decrease or adjust for the variability of these contributing factors.
  • B.2.1.1.2. Uniformity in Biospecimen Collection Practices. The methods used to remove and collect biospecimens from human research participants may influence the quality of the biospecimens collected. Significant research has indicated that during surgical removal of biospecimens the amount of time following the cessation of blood flow to an organ can affect both levels and molecular profiles of target analytes (Spruessel et al. 2004; Lin et al. 2006) . The biospecimen should be preserved as quickly as possible after removal from the patient; e.g., appropriately sized tissue sections snap frozen and/or placed into 10 percent phosphate-buffered formalin, as appropriate. When biospecimens are collected from participants, the site at which the biospecimen is removed (tumor or nontumor, as well as location within the tumor) , any anesthetic being used, the length of time blood flow is blocked from the tissue, any stabilizing agents used to preserve the biospecimen following its removal, the type of fixatives used and the length of time the tissues are exposed to fixatives, and the temperature at which biospecimens are maintained following collection may all affect molecular stability and degradation.

    Prior to the collection or removal of biospecimens, a plan should be in place to allow for the appropriate annotation of the biospecimens. This annotation should include information about the human research participant and timing of collection and processing activities; e.g., the type of clearing agent, the type and temperature of paraffin used to process the biospecimen, etc. (ISBER 2008) . These data should be maintained in a database that can be linked to the biospecimen at all times (see Section B.5, Collecting and Managing Clinical Data, and Section B.6, Biospecimen Resource Informatics) .

  • B.2.1.1.3. Biospecimen Handling Procedures. Every attempt should be made to optimize the handling of biospecimens to minimize resulting molecular changes that may result from the processing activities. This includes not only the temperature and timing of biospecimen processing but also such considerations as the size and volume of the biospecimen that will be stored for future use. Smaller samples allow for minimal cycles of freezing and thawing. When samples are stored in a frozen state, the rate at which they are cooled to the storage temperature can influence the rate at which molecular degradation is allowed to proceed.
• B.2.1.2. Analytic Variables
  When these variables are introduced they lead to differences in the performance of a particular assay. To minimize errors in assay reproducibility, the following considerations should be made:
  • Use of validated assays, where possible
  • Standardized training of technical staff in the performance of the assay
  • Lot uniformity of reagents
  • Inclusion of appropriate type and number of quality control (reference) samples
  • Randomization, when possible
  • Standardized methods for documenting and interpreting testing results