Scientists often use human embryonic stem cells for research because the cells can transform into almost any type in the body. The cells come with a significant ethical problem, though: Harvesting them results in the death of a human embryo.

Now researchers at Lund University in Sweden have developed a technique that allows doctors to harvest stem cells from amniotic fluid and convert them into embryonic-like cells that can grow into other types, including nerve, blood, and heart cells. Extracting the cells, called mesenchymal stem cells (MSCs), does not harm a baby.

Amniotic fluid offers easy access to a rich supply of MSCs. Physicians perform over a million cesarean sections annually, and each surgery provides up to a liter of amniotic fluid that doctors usually discard. Extracting MSCs increases the time to complete a C-section by only 90 seconds and is completely safe for both mother and child, the researchers said in a statement.

The cells do not multiply easily in lab cultures, making it difficult for doctors to obtain a quantity sufficient for many therapies. Scientists can harvest MSCs from other tissues, generally bone marrow, but the marrow contains a very limited number of the cells, and obtaining them requires invasive surgery. Since doctors regularly perform C-sections anyway, harvesting cells from amniotic fluid requires no additional surgery.

Researchers say the MSCs show potential for the treatment of conditions such as cardiovascular disease, diabetes, arthritis, and neurodegenerative disorders.

Roman arrival

A team of scientists from England’s University of Leicester found the first archaeological evidence of Julius Caesar’s invasion of Britain. The new archaeological clues and carbon dating of uncovered pottery and iron weapons support the notion that Caesar’s fleet first landed in Britain in 54 b.c. on the Isle of Thanet, a location that matches Caesar’s personal account of his landing and offers the only bay in the area capable of providing harbor for his 800-ship fleet.

The Leicester researchers said Roman soldiers likely used a defensive ditch (recently excavated by archaeologists) to protect ships landing on the nearby beach. The areas of high ground in Thanet also match Caesar’s description of how British soldiers assembled to oppose the landing but, intimidated by the large Roman fleet, concealed themselves on higher ground.

According to historical records, nearly a century after Caesar’s invasion, the Roman emperor Claudius stormed Britain. “This was the beginning of the permanent Roman occupation of Britain, which included Wales and some of Scotland, and lasted for almost 400 years, suggesting that Claudius later exploited Caesar’s legacy,” lead researcher Colin Haselgrove said. —J.B.

Sensitive ink

Imagine a 3-D tattoo that can tell if you’ve come into contact with a pollutant or other toxin. Engineers at the Massachusetts Institute of Technology recently used live, genetically programmed bacterial cells to create such a tattoo.

The engineers printed a 3-D image of a tree on a wearable patch using ink embedded with living cells. They programmed the cells to light up when they come into contact with certain chemicals: In testing the patch, cells that detected the target chemicals lit up like the branches of a Christmas tree. The researchers hope their technology will enable the manufacture of living cell implants and ingestible drugs. —J.B