CAMBRIDGE, Mass. – Billionaire philanthropists Eli and Edythe Broad are adding $400 million to a joint biomedical venture at Harvard and MIT.

The endowment is on top of $200 million the Broads (BRODES) have already given the project.

The Broads also said Thursday that they're so pleased with how the experimental institute has been working that they plan to convert it into a permanent research organization.

The Broad Institute started in 2004 in the wake of the human genome project.

It brings together scientists to tackle major problems related to cancer, infectious diseases, psychiatric diseases and other conditions.