Lightstone Ventures

Investment decisions are made by the four-person partnership: Mike Carusi, Jean George, Jason Lettmann, and Hank Plain. Each partner sources deals and takes board seats, with no single managing partner holding authority to write checks outside the consensus process. Lettmann and George are the managing directors most frequently named in portfolio company press releases as syndicate leads.

The firm sources through clinical key opinion leader networks at major academic medical centers, relationships with disease-focused foundations, and direct engagement with university technology transfer offices. The Dublin and Singapore offices provide local access to European EMA-track and Asia-Pacific regulatory-stage assets that often do not reach US-focused investors. The partnership's operating backgrounds in medtech also generate inbound referrals from physicians and researchers who know them from prior company-building cycles.

Lightstone Ventures is a traditional institutional venture capital firm, not a family office. It raises blind-pool funds from institutional limited partners — including endowments, foundations, and pension funds — and invests on a fixed management fee and carried interest structure. The firm has no connection to a single-family wealth source.

Lightstone exclusively makes direct investments into operating companies; it does not commit capital to other venture funds as a limited partner. Each investment involves the firm taking a board seat and typically acting as lead or co-lead investor in a priced equity round.

The firm targets early-stage companies, typically those in Series A or Series B financings, and sometimes pre-IPO crossover rounds. The common entry point is a company that has completed initial clinical proof-of-concept — Phase I or Phase II human data for therapeutics, or first-in-human studies for devices — and needs capital to advance through pivotal trials.

Lightstone does not invest outside life sciences. The firm explicitly avoids generalist technology verticals, consumer internet, enterprise software, and financial services. Even within healthcare, the partnership does not invest in healthcare IT, provider services, or payor models unless the company has a clear device or therapeutic component.

Lightstone Ventures is the successor entity to the life sciences practice of Advanced Technology Ventures (ATV). When ATV's healthcare partners — Mike Carusi, Jean George, and Jason Lettmann — raised Lightstone's debut fund in 2014, they effectively completed a spinout, though the two firms shared back-office infrastructure and LPs for a transition period. ATV subsequently wound down its venture operations, and Lightstone now operates fully independently.