Invalidity dossier
US 6251295
Added 9/20/2026, 6:14:28 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6,251,295 B1
Title: Method for recirculation washing of blood cells
Inventor: Craig L. Johnson
Assignee: Nexell Therapeutics Inc (original and listed current assignee)
Application No.: US 09/004,344
Priority/filing date: 1998-01-08
Publication/grant date: 2001-06-26
Legal status (as listed): Expired – Lifetime; anticipated expiration 2018-01-08
Source: https://patents.google.com/patent/US6251295/en
Purpose. The invention relates to recirculation washing of blood cells using a spinning membrane filter, and in particular to recirculation washing of blood cells in a magnetic cell selection apparatus. The supplied text states the invention includes a method, a bag, and a disposable set for recirculation washing of blood cells. It can be used for washing blood cells in a magnetic cell selection instrument, but can also be used for washing whole blood or other blood cell products.
Plain-language scope. The recirculation wash bag is a flexible plastic bag having a top port and a bottom port. In embodiments described, an integral coarse filter comprising a tube of semi-rigid plastic mesh extends from the top port into the bag, providing mild resistance to larger cell aggregates; the bag includes a bubble trap at the top comprising tubing extending into the bag from the top port; and some embodiments include both the semi-rigid integral filter and the bubble trap. The excerpt notes that the prior Isolex® 300i recirculation wash bag had both inlet and outlet ports at the bottom and no top port — a 600 ml bag with ports separated by about 2 inches — and that this bag performed better when occasionally massaged, which was the only way to process more than about 5 x 10^10 cells.
What the excerpt does not establish. The supplied text is explicitly marked as an excerpt with omitted content. It contains no complete claim language, no full written description or drawings, no examples or data, and no figures. It does not establish the full claimed scope, the number or text of claims, or distinctions over cited prior art (Fischel, Schoendorfer, Duff U.S. Pat. No. 5,234,608, Moubayed et al. U.S. Pat. No. 5,536,475, Deniega).
Generated 10/1/2026, 10:02:39 PM
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Litigation summary
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Proceedings on file (0)
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PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.