Fig 2: Mitochondrial malfunction of MELAS fibroblasts is improved following mitochondrial transfer. (a) Representative immunoblot image of mitochondrial OXPHOS subunits (nuclear-encoded NDUFA9 and COX4 and mtDNA-encoded COX2). Actin as loading control. (b–d) Quantitative results of protein expression level normalized to actin. (e, f) Mitochondrial and intracellular ROS detected with MitoSOX™ Red and H2DCFDA, respectively. (g) Mitochondrial membrane potential (??m) measured by TMRE stain and photographed using a fluorescence microscope. FCCP used to dissipate ??m served as negative control. Scale bar, 100 µm. (h) Mitochondrial membrane potential quantitatively analyzed using flow cytometry. * p < 0.05 significantly different when compared to the indicated group. WJ: Wharton's jelly mesenchymal stem cell; Con: control fibroblast from normal human; MFNeg: MELAS fibroblast clone harboring negative mutation burden; MFHi: MELAS fibroblast clone harboring high mutation burden; MFI: mean fluorescence intensity.

Fig 3: CL and low temperature lead to WAT browning, angiogenesis, and an increased number of myofibroblast-like cells. a, b Histological analysis of adipocyte morphology (H&E), adipocytes (PERI), mitochondria (COX4), uncoupling protein 1 (UCP1), blood vessels (CD31), and myofibroblast-like cells (aSMA) in a 5-day CL-316243-treated scWAT and visWAT compared to vehicle-treated control. b Two-week 4 °C-treated scWAT and visWAT compared to 30 °C control. Double-headed arrows mark adipocyte diameter. Arrows point to respective positive signals. c–l Quantifications of adipocyte size and positive signals per field of COX4, UCP1, CD31, and aSMA of CL-316243- and vehicle-, and 30 °C- and 4 °C- treated scWATs and visWATs (>30 adipocytes per field; n = 10 random fields; n = 5 mice per group). PERI, perilipin; COX4, mitochondrial complex 4; UCP1, uncoupling protein 1. Scale bars, 100 µm. NS, not significant. *P < 0.05, **P < 0.01, and ***P < 0.001 by Student’s t-test. Data presented as mean ± s.e.m.

Fig 4: Browning of adipose tissues by cold in xenograft and genetically spontaneous tumour models.a–c, Histological and immunofluorescence staining of BAT in tumour-free mice (a), MMTV-PyMT tumour-bearing mice (b), and ApcMin/+ mice (c) under 30 °C and 4 °C with H&E, UCP1, perilipin, COX4, and CD31, followed by counterstaining with DAPI (blue). Positive signals were randomly quantified (n = 8 or 10 random fields per group). Arrows and arrowheads point to positive signals. d–g, Histological and immunofluorescence staining of sWAT in CRC tumour-bearing mice (d), tumour-free mice (e), MMTV-PyMT tumour-bearing mice (f), and ApcMin/+ mice (g) under 30 °C and 4 °C with H&E, UCP1, perilipin, COX4, and CD31, followed by counterstaining with DAPI (blue). Positive signals were randomly quantified (n = 8 or 10 random fields per group). Arrows and arrowheads point to positive signals. h, Whole-body metabolism of CRC tumour-bearing and tumour-free mice under 30 °C and 4 °C (n = 3 mice per group). All scale bars, 50 µm. Data presented as mean ± s.e.m. Statistical analysis was performed using two-sided unpaired t-test (a–g). Source data

Fig 5: Mitochondrial transfer by WJMSCs contributes to remodel mitochondrial morphology and rescue mitochondrial bioenergetics. (a) Representative image of mitochondrial morphology. Mitochondrial morphology was visualized by transfecting Cox4-DsRed. White rectangle represents highlighted segment enlarged in lower panel. (b, c) The MicroP algorithm categorized mitochondrial morphology into five types: small globe (blue), simple tube (green), twisted tube (orange), donut (red), and branching tube (purple). N = 75-400 mitochondria from 15-30 cells and three independent experiments. (c) Quantitative score of mitochondrial morphology. (d) OXPHOS-linked ATP production was dissected with the addition of ATPase inhibitor oligomycin. (e) OCR analysis. Vertical lines indicate the subsequent addition of the ATPase inhibitor oligomycin, the uncoupling reagent FCCP, and the inhibitors of the electron transport chain rotenone/antimycin A (Rot/AA). (f–i) Histograms individually representing basal (basal OCR), oligomycin-sensitive (ATP-linked OCR), FCCP-stimulated (maximal OCR), and the difference basal and maximal respiration (spare OCR). NS: no significance between the indicated groups. * p < 0.05 significantly different when compared to the indicated group. # p < 0.05 significantly different compared to any other DMSO-treated group. Con: control fibroblast from normal human; MFNeg: MELAS fibroblast clone harboring negative mutation burden; MFHi: MELAS fibroblast clone harboring high mutation burden; OCR: oxygen consumption rate; ECAR: extracellular acidification rate.