**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Mélanie Bézard, The French Cardiac Amyloidosis Reference Center, GRC Amyloid Research Institute, Réseau amylose Mondor, and DHU A-TVB, Créteil, France, Cardiology Department, Assistance Publique des Hôpitaux de Paris, University Hospital Henri Mondor, Créteil, France ; Sorbonne Université, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, Inserm ERL U1164, Adaptation biologique et vieillissement, Paris, France

**Main Body of the Abstract**
Background: AL amyloidosis is a serious systemic disease characterized by the deposition of aggregates of immunoglobulin light chains (LCs) in the form of amyloid fibrils. The organs most often affected are the heart and kidney. Cardiac involvement determines prognosis.
Aim: Our objective was to study the cytotoxic impact of amyloid free LCs in a human cell disease model mimicking AL cardiac amyloidosis (AL-CA).
Methods: Cardiac spheroids were obtained by admixing 15% fibroblasts and 85% human inducible pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) with amyloid free LCs purified from patients’ urine to obtain a homogeneous distribution of LCs within spheroids. Spheroids were further incubated with LCs during one week before analysis. Contractility and calcium transients were analyzed by video microscopy. Cell structure was analyzed by immunolocalization on spheroid frozen sections and Western blotting.
Results: We show that treatment of spheroids with LCs induced in hiPSC-CM: (1) a disturbance in contractility and calcium transient; (2) a decrease in cardiac troponin T protein; (3) an aggregation of SERCA-2a protein.
Conclusion: We have set up a human cellular model of AL-CA, in the form of cardiac spheroids, to study the cytotoxic effects of amyloid proteins. The model enabled us to demonstrate an alteration of calcium transients which could relate to impaired contractility in the presence of LCs. The changes in SERCA-2a and cardiac troponin T proteins further indicated a disturbance of the contractile machinery by means of structural disorganization of cardiomyocytes.



**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Mélanie Bézard, T_he French Cardiac Amyloidosis Reference Center, GRC Amyloid Research Institute, Réseau amylose Mondor, and DHU A-TVB, Créteil, France, Cardiology Department, Assistance Publique des Hôpitaux de Paris, University Hospital Henri Mondor, Créteil, France ; Sorbonne Université, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, Inserm ERL U1164, Adaptation biologique et vieillissement, Paris, France_

**Main Body of the Abstract**
Background: AL amyloidosis is a serious systemic disease characterized by the deposition of aggregates of immunoglobulin light chains (LCs) in the form of amyloid fibrils. The organs most often affected are the heart and kidney. Cardiac involvement determines prognosis.
Aim: Our objective was to study the cytotoxic impact of amyloid free LCs in a human cell disease model mimicking AL cardiac amyloidosis (AL-CA).
Methods: Cardiac spheroids were obtained by admixing 15% fibroblasts and 85% human inducible pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) with amyloid free LCs purified from patients’ urine to obtain a homogeneous distribution of LCs within spheroids. Spheroids were further incubated with LCs during one week before analysis. Contractility and calcium transients were analyzed by video microscopy. Cell structure was analyzed by immunolocalization on spheroid frozen sections and Western blotting.
Results: We show that treatment of spheroids with LCs induced in hiPSC-CM: (1) a disturbance in contractility and calcium transient; (2) a decrease in cardiac troponin T protein; (3) an aggregation of SERCA-2a protein.
Conclusion: We have set up a human cellular model of AL-CA, in the form of cardiac spheroids, to study the cytotoxic effects of amyloid proteins. The model enabled us to demonstrate an alteration of calcium transients which could relate to impaired contractility in the presence of LCs. The changes in SERCA-2a and cardiac troponin T proteins further indicated a disturbance of the contractile machinery by means of structural disorganization of cardiomyocytes.



Amyloid free light chains disturb calcium transients and contractility in an AL cardiac amyloidosis 3D human spheroid model PA30 (#170)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.