Sigilon Therapeutics Inc., a Cambridge, Mass.-based start-up working to encapsulate therapeutic cells for chronic disease inside microspheres invisible to the immune system's normal fibrotic response to foreign implants, has landed a $473 million deal with Eli Lilly & Co. to develop a potential treatment of type 1 diabetes (T1D). The strategic collaboration, which includes $63 million up front plus an equity investment of undisclosed value, marks one of Lilly's biggest insulin-dependent diabetes deals to date, as measured by disclosed initial value, after ill-fated tie-ups with Macrogenics Inc. and Adocia SAS.