Table 1.

Overview over cardiovascular mitochondrial transplantation studies.

Study	Model	Mitochondrial Source	Protocol/Application	Outcomes
Doulamis 2020 [134]	Diabetic and non-diabetic rats	-autologous or from diseased animals -pectoralis major muscle	-ischemia/reperfusion in Langendorff perfused hearts in a T2D model -antegrade i.c.	-Prior: mitochondrial ATP content ↓ in diabetic rats -LVdevP ↑ in both groups (higher in group with healthy mitochondria), LVEDP ↓ + IS ↓in both groups →no difference in cardiac function, IS and CBF between both groups (except LVdevP) -tissue ATP ↑ (higher in group with healthy mitochondria)
	rats	-syngeneic -pectoralis major muscle	-for biodistribution -antegrade i.c.	-distributed throughout the heart
		-human cardiac fibroblasts	-for biodistribution -retrograde i.c.	-distributed within myocardial fibers
Ramirez-Barbieri 2019 [132]	mice	-syngeneic + allogeneic -gastrocnemius + quadriceps femoris muscle	-single or serial i.p. in a skin graft model	-no inflammatory or autoimmune responses (IgM antibodies, IL4, TNF-α, skin graft survival time, lymphocyte infiltration, free mtDNA, histological changes in heart and lung)
Moskowitzova 2019 [130]	mice	-syngeneic -gastrocnemius muscle	-heart transplantation -29h cold ischemia time -i.c. before transplantation + 5 min after transplantation	-beating score ↑, EF ↑and FS ↑, necrosis and inflammatory cell infiltration ↓ -no differences in TUNEL+ nuclei -myocardial injury (contraction bands) in vehicle groups
	rats		-antegrade i.c.	-diffuse distribution in the heart
Guariento 2020 [125]	pigs	-autologous -pectoralis muscle	-circulatory death/Ischemia/cardioplegia/reperfusion -single or two injections (2nd after 2 h of ex-situ heart perfusion and reperfusion for additional 2 h)	-LV/ventricular peak developed pressure ↑, FS ↑, myocardial oxygen consumption ↑, IS ↓
Guariento 2020 [126]	pigs	-autologous --pectoralis major muscle	-preischemic intracoronary single or serially injections -ischemia/reperfusion	-CBF ↑ pre-RI period and during reperfusion -myocardial function ↑ (EF ↑ + LV Pdev ↑, LV dP/dt max↑, LV Ped ↓ SS ↑, FS ↑), IS ↓; necrosis + edema ↓, preserved mitochondrial structure → no differences between single and serial injections
McCully 2009 [129]	rabbits	-allogenic -left ventricle	-ischemia/reperfusion-in excised hearts	-LVPDP + SS + ATP content ↑, LVEDP + IS + CK-MB and cTnI, caspase-3-like activity ↓, -no differences in TUNEL+ nuclei -mitochondria viable and detectable; located near the myocytes
			-frozen mitochondria/ mitochondrial components or mitochondrial DNA/RNA	-LVPDP ↓, LVEDP ↑, SS ↓ + IS ↑, RCI ↓, oxygen consumption ↓ compared to fresh mitochondria
Masuzawa 2013 [128]	in vivo: rabbits	-autologous -pectoralis major muscle optical mapping: liver mitochondria	-ischemia/reperfusion recovery for 2h or 28days	-no arrhythmogenicity, decreased necrosis, enhanced postischemic function, IS ↓, CK-MB ↓ and cTnI ↓, increase of tissue ATP content in AAR, percent systolic wall thickening ↑ compared to vehicle, segmental hypokinesis in vehicles TUNEL+ nuclei ↓ and caspase 3 activity ↓, no inflammatory effect (hsCRP↓, IL6↓, TNFa↓), no antimitochondrial antibodies after 4 weeks -proteomic analyses: generation of precursor metabolites for energy ↑ and cellular respiration↑ -mitochondria in the interstitial spaces surrounding cardiomyocytes at 0, 2, 4, 8 and 24 h following injection-fraction of the labeled mitochondria within cardiomyocytes 2 h after injection
		-xenogeneic human mitochondria from HeLa cells	separate group: -biodistribution -injection in tissue	-majority of mitochondria in the interstitial spaces, partly localized within cardiomyocytes
	in vitro	- HeLa- derived intact and sonicated mitochondria	subgroup: -co culture of HeLa- derived intact and sonicated mitochondria and human PBMCs	no upregulation of cytokines associated with rejection (IL-1, IL-4, IL-6, IL-12, IL-18, IP-10 and macrophage inflammatory protein-1a and -1b) EGF↑, GRO↑, IL-6↑ and MCP-3↑ →associated with enhanced postinfarct cardiac function
	in vitro	-syngeneic -rat liver mitochondria	subgroup: -internalization -neonatal rat cardiomyocytes cocultured with mitochondria	-majority of mitochondria internalized within 24 h of incubation -oxygen consumption ↑
	in vitro	-xenogeneic -HeLa cell mitochondria	subgroup: -internalization -cardiomyocytes incubated with mitochondria	-mitochondria adherent to cells within 2 h and internalized within 8–24 h -no colocalization with lysosomes or autophagosomes
Kaza 2017 [127]	pigs	-autologous -pectoralis major muscle	-ischemia/reperfusion -subendocardial injections -4 weeks recovery	-IS↓, no immune and inflammatory response and cytokine activation, no arrhythmia, -mitochondrial damage and contraction bands in vehicle hearts -no differences in systolic function (EF, FS and global circumferential strain)
Blitzer 2020 [122]	pigs	-autologous -pectoralis major muscle	-ischemia/reperfusion -delayed i.c. application	-LVEF↑, EF ↑, FS ↑, fractional area change, IS ↓, LV EDP ↓ -maximal rate of rise of LV pressure ↑, SS↑, LVFS↑, LVFAC↑, transient CBF ↑
Emani 2017 [124]	children	-autologous -rectus abdominis muscle	-epicardial injection 2–15 d after ECMO cannulation	-4/5 improvement in ventricular function separation from ECMO, 3/5 survived -no signs of immune responses (respiratory and renal status)
Shin 2019 [116]	pigs	-autologous -pectoralis major muscle	safety and biodistribution: -i.c. serially autologous injections, increasing concentrations subgroup: -efficacy in ischemia/reperfusion	-mitochondria located in the LV, partly in the arterial sheath and in the right carotid artery, small amount in descending aorta -mitochondria within cardiomyocytes, interstitial spaces and the vascular walls - enhanced regional and global LV function; CBF ↑ in higher concentrations; CBF↑ i.c., no increase after injection -Improved myocardial function (FS↑, proportion LV fractional area change, EF ↑), IS↓
			-devitalized mitochondria + mitochondria from HeLa- and HeLa-p0 cells	-HeLa mitochondria: CBF ↑ CBF ↑ after i.c. injection of ATP but shorter duration
Weixler 2020 [133]	in vitro	-autologous -heart muscle, soleus muscle, gastrocnemius muscle	-internalization -neonatal rat RV cardiomyocytes	-no differences in ATP content or mitochondrial internalization
	in vivo: pigs	-autologous -gastrocnemius muscle	-injection into RV free wall after pulmonary artery banding	-TAPSE ↑, contractile function↑, apoptosis ↓, myocardial fibrosis↓
Cowan 2016 [123]	rabbits	-human adult cardiac fibroblasts	-imaging -Langendorff hearts -global and regional Ischemia/reperfusion -i.c. or local injection	-most of mitochondria remained within heart throughout reperfusion -majority within interstitial spaces between cardiomyocytes, partly co localization with cardiomyocytes
		-autologous -liver mitochondria	function: -no ischemia or regional ischemia/reperfusion -antegrade i.c.	myocardial function ↑ (EDP↓, IS ↓, SS ↑ and dP/dt ↑)