Lend-a-Hand was an organisation created by Igrix to change the course of Earth's history in 1966. Igrix placed Mr Love as the "head" of the company, and while he had converted some humans to work for Lend-a-Hand to build up the numbers, he later grew an entire army of artificially grown biotech beings grown from Kustollon genestuff. The Ninth Doctor described the girls as "an intelligent, organic machine", who "obey genetic instructions".
As part of his plan to change history, Igrix sent his girls to ensure humanity was always satisfied and not need to venture out into space. He also made sure that any scientists who would disrupt this and be unhappy would get killed. The girls had low-level telepathy so they could tell what a human wanted and could amplify endorphins in the human brain.
One of these scientists was Peter Cobb, husband of Charlotte. Charlotte investigated Lend-a-Hand and discovered what had happened to the girls there. She killed and captured one of the girls made from alien DNA, and created a chemical that would dissolve them as a way of fighting back.
Igrix sent his girls to kill Charlotte and the Ninth Doctor, who had just arrived and began to wise up to their plans. Rose Tyler and Shirley Gilbert came for an interview at the Lend-a-Hand headquarters, where they saw what truly happened to the girls and fled the building.
Later, after every girl was infected with the "human virus" the Doctor made, they were instructed to obey the genetic instructions of Rose Tyler and become humans, although some who did not have an intelligence fell apart. The Doctor explained that they would adapt to life on Earth after a bit, as that was what they were now programmed for. (COMIC: The Love Invasion)