Penumbra

Penumbra began with a clinical question that, until the early 2000s, did not have an engineered answer: when a clot lodges itself in an artery of the brain, can a clinician thread a catheter to the obstruction and physically remove it, rather than wait for a drug to dissolve it? The neurointerventionalist Arani Bose and the lawyer-turned-operator Adam Elsesser took up that question in Alameda in 2004, and twenty-two years later Penumbra is the medical-device manufacturer whose stroke-treatment systems sit in the cath labs of most major American stroke centres.

The company designs and manufactures vascular thromboembolectomy systems — precision catheters and aspiration platforms used in interventional neurology and peripheral vascular medicine. Its principal product line, the Penumbra System, is the standard of care for the mechanical removal of clots in acute ischaemic stroke; adjacent product lines treat pulmonary embolism, deep vein thrombosis, and acute limb ischaemia. The firm’s regulated manufacturing, design engineering, regulatory affairs, and clinical-training operations are concentrated on a single Alameda campus across the bay from San Francisco.

Among American medical-device firms of its scale, Penumbra is unusual for the degree to which its operation is vertically integrated and geographically concentrated: design, prototyping, regulated manufacturing, and clinical training all happen within walking distance of one another. The firm went public on the New York Stock Exchange in 2015 after eleven years of private operation; in January 2026, Boston Scientific announced its agreement to acquire the company at $374 per share, valuing it at approximately $14.5 billion. The acquisition is expected to close later in the year, at which point Penumbra’s manufacturing operations will become a Boston Scientific business unit.

The practice has worked with Penumbra at the Alameda site on Lean process implementation across regulated-manufacturing operations.