In this undated file photo, a medical worker at the hospital performs a test on a biosafety kit. (PHOTO BY WANG JING / CHINA DAILY)

GUANGZHOU - A bag containing hemopoietic stem cells for a leukemia patient was shipped from Guangzhou, Guangdong province, to the Hong Kong Special Administrative Region on a high-speed train on Thursday.

The stem cell donor, a 35-year-old man from Yangjiang, Guangdong, registered as a volunteer for hemopoietic stem cell donation five years ago

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The shipment marked the first overseas donation of non-frozen hemopoietic stem cells from the Chinese mainland in three years since the outbreak of the COVID-19 pandemic, Nanfang Daily reported.

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The stem cell donor, a 35-year-old man from Yangjiang, Guangdong, underwent a four-hour procedure in Guangzhou to allow doctors to collect them.

He registered as a volunteer for hemopoietic stem cell donation five years ago. Weighing less than 50 kilograms when he was matched with the leukemia patient in Hong Kong, the 170-centimeter-tall man ate extra food and gained five kilograms as he prepared for the donation.

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He has a 15-centimeter-long scar on his abdomen from a surgery in childhood and a smaller than average heart, which introduced some potential risks. But with the healthy weight gain, the man was eventually cleared by the doctors.