    <SEC-DOCUMENT>0001453687-25-000140-index.html : 20251218
    <SEC-HEADER>0001453687-25-000140.hdr.sgml : 20251218
    <ACCEPTANCE-DATETIME>20251218161302
    ACCESSION NUMBER:		0001453687-25-000140
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		15
    CONFORMED PERIOD OF REPORT:	20251216
    ITEM INFORMATION:		Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers
    ITEM INFORMATION:		Amendments to the Registrant's Code of Ethics, or Waiver of a Provision of the Code of Ethics
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20251218
    DATE AS OF CHANGE:		20251218

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			Cartesian Therapeutics, Inc.
    		CENTRAL INDEX KEY:			0001453687
    		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
    		ORGANIZATION NAME:           	03 Life Sciences
    		EIN:				000000000
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-37798
    		FILM NUMBER:		251583232

    	BUSINESS ADDRESS:
    		STREET 1:		7495 NEW HORIZON WAY
    		CITY:			FREDERICK
    		STATE:			MD
    		ZIP:			21703
    		BUSINESS PHONE:		301-348-8698

    	MAIL ADDRESS:
    		STREET 1:		7495 NEW HORIZON WAY
    		CITY:			FREDERICK
    		STATE:			MD
    		ZIP:			21703

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	SELECTA BIOSCIENCES INC
    		DATE OF NAME CHANGE:	20090109
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>rnac-20251216.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: rnac-20251216.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-14.1
    <SEQUENCE>2
    <FILENAME>codeofethicsandbusinesscon.htm
    <DESCRIPTION>EX-14.1
    <TEXT>
    Document 2 - file: codeofethicsandbusinesscon.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>3
    <FILENAME>pressreleaseofcartesianthe.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 3 - file: pressreleaseofcartesianthe.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>4
    <FILENAME>rnac-20251216.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 4 - file: rnac-20251216.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>5
    <FILENAME>rnac-20251216_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: rnac-20251216_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>6
    <FILENAME>rnac-20251216_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: rnac-20251216_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>cartesian_logoa.jpg
    <TEXT>
    Document 7 - file: cartesian_logoa.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>9
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 9 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>11
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 11 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>13
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 13 - file: FilingSummary.html

    Document 13 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>15
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 15 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>16
    <FILENAME>0001453687-25-000140-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: 0001453687-25-000140-xbrl.zip

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>17
    <FILENAME>rnac-20251216_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 17 - file: rnac-20251216_htm.html

    Document 17 - RAW XML: rnac-20251216_htm.xml

    </DOCUMENT>
    </SEC-DOCUMENT>