Filing of definitive proxy statement

MaxCyte Inc.

(ÒMaxCyteÓ or the ÒCompanyÓ)

Update on Proposed Cancellation of Admission of Common Stock to Trading on AIM - Filing of definitive proxy statement with the SEC

ROCKVILLE, MD, LONDON, UK, 28 April 2025 Ñ MaxCyte, Inc., (NASDAQ: MXCT; LSE: MXCT), a leading, cell-engineering focused company providing enabling platform technologies to advance the discovery, development, and commercialization of next-generation cell therapeutics, announces that, following its notice on 15 April 2025 of the CompanyÕs intention to cancel trading of its ordinary shares on AIM, the Company intends to file a definitive proxy statement in relation to seeking stockholder approval for the AIM Delisting and other matters to be voted on at the annual meeting with the SEC later today.

The definitive proxy statement will be sent to stockholders and made available on MaxCyteÕs website at https://investors.maxcyte.com later today.

The Company will seek stockholder approval for the AIM Delisting at its annual meeting of stockholders which will be held at 11.00 a.m. Eastern Time (4.00 p.m.UK time) on Wednesday 18 June 2025 at 9713 Key West Avenue, Suite 400, Rockville, Maryland, 20850.

Updated Anticipated Timetable of Key Events

Forward-Looking Statements

This announcement contains Òforward-looking statementsÓ within the meaning of Section 27A of the U.S. Securities Act of 1933, as amended, and Section 21E of the U.S. Securities Exchange Act of 1934, as amended, including in respect of the anticipated timeline of key events related to the proposed AIM Delisting. All statements other than statements of historical fact contained in this announcement are forward-looking statements. Forward-looking statements usually relate to future events. Forward-looking statements are often identified by the words Òbelieve,Ó Òexpect,Ó Òanticipate,Ó Òplan,Ó Òintend,Ó Òforesee,Ó Òshould,Ó Òwould,Ó Òcould,Ó Òmay,Ó and similar expressions, including the negative thereof. The absence of these words, however, does not mean that the statements are not forward-looking. These forward-looking statements are based on the CompanyÕs current expectations, beliefs and assumptions concerning future developments and their potential effect on the Company. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future developments affecting the Company will be those that it anticipates.

All of the CompanyÕs forward-looking statements involve known and unknown risks and uncertainties, some of which are significant or beyond its control and involve assumptions that could cause actual results to differ materially from the CompanyÕs historical experience and its present expectations. These forward-looking statements are subject to risks and uncertainties, including, among other things, risks that the stockholder vote for the AIM Delisting may not be obtained and that the anticipated trading volume in the CompanyÕs equity securities on Nasdaq may not materialise, as well as those risks and uncertainties described in the CompanyÕs latest Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and other documents filed from time to time by the Company with the SEC. The Company wishes to caution investors not to place undue reliance on any forward-looking statements, which speak only as of the date hereof. The Company undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except to the extent required by law.

About MaxCyte

At MaxCyte, we pursue cell engineering excellence to maximize the potential of cells to improve patientsÕ lives. We have spent more than 25 years honing our expertise by building best-in-class platforms, perfecting the art of the transfection workflow, and venturing beyond todayÕs processes to innovate tomorrowÕs solutions. Our ExPERTª platform, which is based on our Flow Electroporation¨technology, has been designed to support the rapidly expanding cell therapy market and can be utilized across the continuum of the high-growth cell therapy sector, from discovery and development through commercialization of next-generation, cell-based medicines. The ExPERT family of products includes: four instruments, the ATxª, STxª, GTxª and VLx ª; a portfolio of proprietary related processing assemblies or disposables; and software protocols, all supported by a robust worldwide intellectual property portfolio. By providing our partners with the right technology platform, as well as scientific, technical and regulatory support, we aim to guide them on their journey to transform human health. Learn more at maxcyte.com and follow us on X and LinkedIn .

Terms used but not defined in this announcement have the same meaning as set out in the CompanyÕs announcement released at 7:00 a.m. on 15 April 2025.

MaxCyte Contacts:

US IR Adviser

Gilmartin Group

David Deuchler, CFA

+1 415-937-5400

ir@maxcyte.com

US Media Relations

Spectrum Science

Jordan Vines

+1 540-629-3137

jvines@spectrumscience.com

Nominated Adviser and Joint Corporate Broker

Panmure Liberum

Emma Earl / Mark Rogers

Corporate Broking

Rupert Dearden

+44 (0)20 7886 2500

UK IR Adviser

ICR Healthcare

Mary-Jane Elliott

Chris Welsh

+44 (0)203 709 5700

maxcyte@icrheatlhcare.com