1) High-tech, high growth entrepreneurship should be central to an innovation district, but there's no evidence for high concentrations. Essentially these are redevelopment plans for medical centers. In most cases, there's no example of high-tech, high-growth in the innovation district.
2) Most successful examples -- which Katz & Wagner do not study in depth -- do not involve medical centers (Kendall Square, South Lake Union). These also don't see to have involved extensive use of public funds or centralized urban planning 9need (need more research to be sure).
3) Innovation Districts Katz & Wagner study extensively seem to be determined by donor support. (All reports include disclaimer that donors do not influence report.)