Table 1 Methods for tumor interstitial fluid isolation

Glass capillaries

Insertion by blunt dissection in vivo

Fluid from tumor periphery or sectioned surface

In vivo native fluid

Bleeding and inflammation, cellular disruption

High level of intracellular enzymes in isolated fluid

[40]

Implantable chambers

Chronically implanted

Fluid draining from central part of tumor

In vivo native fluid, continuous and repeated sampling

Inflammation in early phases, scar formation

Requires chronic restraining of animal

[41]

Implanted wicks

Implanted acutely or chronically

Fluid absorbed into wicks during implantation

In vivo, native fluid

Bleeding and inflammation, cellular disruption

Chronic implantation more representative than acute

[43]

Microdialysis

Insertion of semipermeable membrane

Substances diffusing across membrane

In vivo continuous and repeated sampling

Inflammation, incomplete recovery, dilute fluid

Recovery especially low for macromolecules

Reviewed in [45]

Capillary ultrafiltration

Negative pressure applied to semipermeable membrane

Substances transported by bulk flow across membrane

In vivo continuous and repeated sampling

Inflammation, incomplete recovery

Recovery especially low for macromolecules

[60]

Tissue centrifugation

Exposure of excised tissue to increased G-force

Fluid from tumor periphery or bone marrow

Native fluid

Ex vivo single samples

Composition validated by extracellular tracers

[61, 77]

Tissue elution

Elution of minced tissue

Substances dissolved in elution buffer

Technically easy

Ex vivo single samples, dilute fluid

Contamination by intracellular proteins likely

[67]