Sec Form 4 Filing - Hoge Elizabeth @ Cartesian Therapeutics, Inc. - 2024-04-08

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Hoge Elizabeth 2. Issuer Name and Ticker or Trading Symbol Cartesian Therapeutics, Inc. [ RNAC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O CARTESIAN THERAPEUTICS, INC., 704 QUINCE ORCHARD RD 3. Date of Earliest Transaction (MM/DD/YY) 04/08/2024 (Street) GAITHERSBURG, MD20878 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 04/08/2024 C 2,926,764 A 3,036,887 I as trustee ( 2 ) Common Stock 04/08/2024 C 491,853 A 506,377 I by spouse

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A Non-Voting Convertible Preferred Stock ( 1 ) 04/08/2024 C 87,802.95 ( 1 ) ( 1 ) Common Stock 2,926,764 $ 0 101,953.444 I by trust ( 2 ) Series A Non-Voting Convertible Preferred Stock ( 1 ) 04/08/2024 C 14,755.609 ( 1 ) ( 1 ) Common Stock 491,853 $ 0 0 I by spouse

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Hoge Elizabeth C/O CARTESIAN THERAPEUTICS, INC. 704 QUINCE ORCHARD RD GAITHERSBURG, MD20878 X Seven One Eight Three Four Irrevocable Trust C/O CARTESIAN THERAPEUTICS, INC. 704 QUINCE ORCHARD RD GAITHERSBURG, MD20878 X Signatures /s/ Murat Kalayoglu, Authorized Person 04/10/2024 Signature of Reporting Person Date /s/ Murat Kalayoglu, Authorized Person 04/10/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Following the approval by the stockholders of the issuer of the conversion of the Series A Non-Voting Convertible Preferred Stock of the issuer ("Series A Preferred Stock") into shares of common stock of the issuer ("Common Stock"), each share of Series A Preferred Stock automatically converted into 33-1/3 shares of Common Stock, subject to certain limitations, including that a holder of Series A Preferred Stock is prohibited from converting shares of Series Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 19.9% of the total number of shares of Common Stock issued and outstanding immediately after giving effect to such conversion. ( 2 )Shares are owned directly by Seven One Eight Three Four Irrevocable Trust (the "Trust"). The reporting person is a trustee and beneficiary of the Trust.

Remarks: Exhibits 24.1 and 24.2 filed herewith.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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