Cells send first signals of disease. Scientists now find way to boost this message

Every second, our cells secrete nano-sized bubbles called exosomes. These particles were once thought as just trash being released by cells, but that changed in the late 2000s when experts found exosomes have a ‘signalling role’ and can reveal the earliest signs of diseases such as Parkinson’s, Alzheimer’s or even heart trouble, years before onset. Exosomes are found in tissue, blood, urine and saliva, but their extraction and separation from impurities meant long hours — even days — in lab centrifuges and use of harsh chemicals for isolation. Indian-origin researcher Kshipra Kapoor and her team from Rice University and MD Anderson Cancer Center, Houston, have developed a method that isolates exosomes from blood in just 20 minutes, removing 95% of impurities and recovering nearly 90% of them for a reliable analysis. Kapoor spoke to TOI about the development. Excerpts:

■ What exactly are exosomes?A: Exosomes are tiny, membrane-bound bubbles (about 30–150 nanometres) released by nearly all cells. Think of them as nature’s “courier parcels”: they carry molecular messages — proteins, lipids, and genetic material like RNA — from one cell to another. Scientists first saw related cell-shed particles in the 1960s, but exosomes as we define them today were described in the 1980s in studies on how red blood cells mature. By the late 2000s, it became clear these vesicles weren’t debris — they were organised messengers.
■ They were first thought of as “cellular trash”?A: Yes. Early on, exosomes looked like a convenient way for cells to eject excess material. Two things changed that view: researchers found exosomes were packed with selected proteins and RNAs, not random trash. And experiments later showed that when one cell’s exosomes are taken up by another, they can change the recipient cell’s behaviour. That’s classic signalling, not waste disposal.
■ Could you describe your test?A: During my PhD, I developed an exclusion method that isolated very pure exosomes in minutes, without harsh chemicals and long spinning hours in centrifuges. The aim was to give clinicians a lab-friendly way to pull exosomes out of blood or other fluids. I was inspired by refinement techniques used by the oil and gas industry. Next, we pair the purification with a microfluidic sensor to capture exosomes and read out their presence/signature.

■ How do exosomes signal diseases?A: Because exosomes are released by living tissues, their cargo reflects what’s happening inside those tissues. A stressed liver cell releases exosomes enriched in liver-specific molecules (certain proteins or RNAs). Tumour cells do the same with cancer-linked markers. So, doctors collect a small blood sample, isolate exosomes using our rapid method, measure specific markers (proteins or RNAs) using our sensor chips or sequencing panels and use algorithms to compare healthy and diseased signatures.
■ How much exosome material do you need for a reliable diagnosis?A: It depends on the test, but the amounts are small. Today, a few hundred microlitres — around 1 mL of blood — is typically sufficient for multiple measurements. Our nearterm goal is finger-prick volumes as sensors and chemistry continue to improve.
■ How will your test work in the real world?A: Our vision is this: You visit a diagnostics centre where they draw a tiny blood sample. The exosomes in the blood are purified in minutes and flowed over a multi-marker sensor panel. A software report then translates the exosome signature into an actionable readout: “low risk”, “needs follow-up imaging” or “monitor treatment response”.