In biotech parks across the Yangtze River Delta, dozens of start-ups are working to develop drugs to treat China's biggest emerging diseases - from diabetes and Hepatitis B to respiratory illnesses and cancer.

It's early days, but firms like Hua Medicine and Innovent Biologics embody China's hopes for competitive biomedical innovation. And their Chinese-born, Western-educated founders represent the long-awaited return of the nation's brightest life scientists.

From school in the late 1970s and 1980s, when only elite students gained entry into China's few biochemistry and molecular biology programs, they left China, graduated and worked their way up to senior positions in the world's top pharmaceutical companies.

It took the jobs squeeze of the 2008 global financial crisis and fresh government incentives - from state-of-the-art research labs to grants, loans and government venture capital - to prise them from international careers to launch their own start-ups in China.

"If returnees want to do innovation, in academia there is traditional resistance and old practices," said Huiyao Wang at the Center for China & Globalization. "It's the private sector that really attracts people to start new ventures."

China has committed more than $300 billion to science and technology, with biotech one of seven pillar industries in the latest Five-Year Plan. Biomedical research investment jumped more than four-fold in 2007-12, though it is still dwarfed by spending in the United States and Europe, according to a 2014 study in the New England Journal of Medicine.

Returnee firms have listed in New York and London, work closely with 'Big Pharma' and attract investment from US venture capital and multinationals.