Myogenin-expressing fibroblast-like cell (MEFLC) line and construction method and use thereof

1 . A myogenin-expressing fibroblast-like cell (MEFLC) line deposited in the Guangdong Microbial Culture Collection Center (GDMCC) on Apr. 23, 2022 with an accession number of GDMCC NO: 62409.

2 . A medium for cultivating the MEFLC line according to claim 1 , comprising: high-sugar Dulbecco's Modified Eagle Medium (DMEM), fetal bovine serum (FBS) with a volume content of 10%, non-essential amino acid (NEAA) with a volume content of 1%, PS with a volume content of 1%, and doxycycline hyclate (Dox), wherein a final concentration of the Dox in the medium is 2 μg/mL.

3 . A construction method for the MEFLC line according to claim 1 , comprising the following steps:

1) Constructing an MYOG gene-containing lentivirus;

2) Infecting a human induced pluripotent stem cell (iPSC) line with the MYOG gene-containing lentivirus, inducing an expression of an MYOG gene, and screening out a first positive monoclonal cell line;

3) Subjecting the first positive monoclonal cell line to an expanded cultivation, and continuously inducing the expression of the MYOG gene; and

4) Changing cultivation conditions, continuously inducing the expression of the MYOG gene, and screening out a second positive monoclonal cell line to ensure a purity of MYOG-positive cells until a cell morphology of the MYOG-positive cells changes significantly into fibroblastoid cells to obtain the MEFLC line.

4 . The construction method according to claim 3 , wherein in step 1), the MYOG gene-containing lentivirus is a lentivirus carrying a tetracycline-inducible system; and the MYOG gene-containing lentivirus is a pCW-MYOG-T2A-Puro lentivirus, and a construction method for the pCW-MYOG-T2A-Puro lentivirus comprises:

1) Construction of a lentiviral expression vector: subcloning MYOG cDNA and a puromycin resistance gene into a pCW-Cas9-Blast vector through a conventional molecular cloning method to replace Cas9 and Blast genes in the pCW-Cas9-Blast vector to obtain a pCW-MYOG plasmid; and

2) Lentivirus package:

A. inoculating HEK293T cells into a 6-well plate and cultivating the HEK293T cells with a D10 medium until a cell confluency reaches 70% to 80% ready for a transfection, wherein the D10 medium comprises DMEM and FBS with a volume content of 10%;

B. 1 h before the transfection, removing the D10 medium and adding a pre-warmed serum-free OptiMEM medium at 2 mL/well;

C. using a Lipofectamine 2000 reagent to co-transfect the HEK293T cells with pCW-MYOG, pVSVg, and psPAX2 according to product instructions;

D. changing the pre-warmed serum-free OptiMEM medium to a medium comprising DMEM, FBS with a volume content of 10%, and bovine serum albumin (BSA) with a volume content of 1%;

E. further cultivating the HEK293T cells for 60 h, and collecting and centrifuging a culture at 3,000 rpm and 4° C. for 10 min to remove cell debris to obtain a first resulting supernatant;

F. filtering the first resulting supernatant through a 0.45 μm low protein binding filter membrane to remove cell debris to obtain a virus-containing filtrate; and

G. mixing the virus-containing filtrate and a sucrose buffer with a mass percentage content of 10% in a volume ratio of 4:1 to obtain a resulting mixture, adding the resulting mixture to a centrifuge tube, and centrifuging at 10,000 g and 4° C. for 4 h, wherein the sucrose buffer comprises 50 mM Tris-Hcl, 100 mM NaCl, and 0.5 mM EDTA and has a pH of 7.4; and discarding a second resulting supernatant, draining the centrifuge tube on absorbent paper for 3 min, adding PBS for a resuspension, and storing a resulting suspension at −80° C.

5 . The construction method according to claim 4 , wherein

an inducer for inducing the expression of the MYOG gene is Dox; and

each of the first positive monoclonal cell line and the second positive monoclonal cell line is screened out by adding puromycin to a medium.

6 . The construction method according to claim 3 , wherein a medium for the expanded cultivation of the first positive monoclonal cell line is a StemUp medium.

7 . The construction method according to claim 3 , wherein the step of changing the cultivation conditions comprises using a medium comprising high-sugar DMEM, FBS with a volume content of 10%, NEAA with a volume content of 1%, PS with a volume content of 1%, and Dox, wherein a final concentration of the Dox in the medium is 2 μg/mL.

8 . A method of a use of the MEFLC line according to claim 1 in a preparation of a drug for treating a cardiovascular disease (CVD) caused by cardiomyocyte apoptosis, comprising:

using the MEFLC line as a support cell drug for a cardiomyocyte infusion by mixing the MEFLC line with a cardiomyocyte for injection or using the MEFLC line alone for injection;

wherein a dosage form of the drug is an injection; and

the CVD caused by the cardiomyocyte apoptosis is myocardial infarction (MI), heart failure, or coronary heart disease (CHD).

9 . A method of a use of the MEFLC line according to claim 1 as an additive for reducing an apoptosis proportion when a cryopreserved cardiomyocyte is resuscitated or a cardiomyocyte is in a hypoxia/reactive oxygen species (ROS)/doxorubicin environment.

10 . A method of a use of the MEFLC line according to claim 1 in a preparation of an injectable drug for treating MI, heart failure, or CHD.

11 . The construction method according to claim 4 , wherein a medium for the expanded cultivation of the first positive monoclonal cell line is a StemUp medium.

12 . The construction method according to claim 5 , wherein a medium for the expanded cultivation of the first positive monoclonal cell line is a StemUp medium.

13 . The construction method according to claim 4 , wherein the step of changing the cultivation conditions comprises using a medium comprising high-sugar DMEM, FBS with a volume content of 10%, NEAA with a volume content of 1%, PS with a volume content of 1%, and Dox, wherein a final concentration of the Dox in the medium is 2 μg/mL.

14 . The construction method according to claim 5 , wherein the step of changing the cultivation conditions comprises using a medium comprising high-sugar DMEM, FBS with a volume content of 10%, NEAA with a volume content of 1%, PS with a volume content of 1%, and Dox, wherein a final concentration of the Dox in the medium is 2 μg/mL.