Article

Transplanted embryonic neurons integrate into adult neocortical circuits

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Abstract

The ability of the adult mammalian brain to compensate for neuronal loss caused by injury or disease is very limited. Transplantation aims to replace lost neurons, but the extent to which new neurons can integrate into existing circuits is unknown. Here, using chronic in vivo two-photon imaging, we show that embryonic neurons transplanted into the visual cortex of adult mice mature into bona fide pyramidal cells with selective pruning of basal dendrites, achieving adult-like densities of dendritic spines and axonal boutons within 4–8 weeks. Monosynaptic tracing experiments reveal that grafted neurons receive area-specific, afferent inputs matching those of pyramidal neurons in the normal visual cortex, including topographically organized geniculo-cortical connections. Furthermore, stimulus-selective responses refine over the course of many weeks and finally become indistinguishable from those of host neurons. Thus, grafted neurons can integrate with great specificity into neocortical circuits that normally never incorporate new neurons in the adult brain.

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Change history

  • Corrected online 09 November 2016

    Minor changes were made to Figs 4, 5 and Extended Data Fig. 8.

  • Corrected online 17 November 2016

    The resolution of Fig. 4 was increased.

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    Acknowledgements

    We thank D. Franzen, G. Jäger, T. Simon, V. Staiger, H. Tultschin and F. Voss for technical support, and A. Lepier for viral vector expertise. M. Sperling, P. Goltstein and A. Grade helped with hardware and software. This work was supported by the German Research Foundation (SFB 870 ‘Neuronal Circuits’: M.G., L.D., K.-K.C., T.B. and M.H.; SPP 1757: M.G. and L.D.), the Advanced ERC grant ChroNeuroRepair (M.G.), the Helmholtz Alliance Icemed (M.G.), the Boehringer Ingelheim Fonds (S.F.), and the Max Planck Society (S.F., T.B. and M.H.).

    Author information

      • Susanne Falkner
      •  & Sofia Grade

      These authors contributed equally to this work.

      • Magdalena Götz
      •  & Mark Hübener

      These authors jointly supervised this work.

    Affiliations

    1. Max Planck Institute of Neurobiology, D-82152 Martinsried, Germany

      • Susanne Falkner
      • , Tobias Bonhoeffer
      •  & Mark Hübener

    2. Physiological Genomics, Biomedical Center, Ludwig-Maximilians University Munich, D-82152 Planegg, Germany

      • Sofia Grade
      • , Leda Dimou
      •  & Magdalena Götz

    3. Institute of Stem Cell Research, Helmholtz Center Munich, German Research Center for Environmental Health, D-85764 Neuherberg, Germany

      • Sofia Grade
      • , Leda Dimou
      •  & Magdalena Götz

    4. SYNERGY, Excellence Cluster of Systems Neurology, Biomedical Center, Ludwig-Maximilians University Munich, D-82152 Planegg , Germany

      • Leda Dimou
      •  & Magdalena Götz

    5. Max von Pettenkofer Institute and Gene Center, Ludwig-Maximilians University Munich, D-81377 Munich, Germany

      • Karl-Klaus Conzelmann

    Authors

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    Contributions

    The original idea for the study came from M.G. M.G, M.H. and T.B. then initiated the study and planned the experimental approach. S.F., S.G., M.G., M.H. and L.D. designed the experiments; S.F. performed in vivo imaging experiments and analysis; S.G. performed the experiments in fixed tissue including connectivity experiments and analysis. M.G. and L.D. provided the lesion model. K.-K.C. provided the rabies virus and expertise for its use for monosynaptic tracing. Finally, M.G., M.H., S.G. and S.F. wrote the paper with input from T.B., L.D. and K.-K.C.

    Competing interests

    The authors declare no competing financial interests.

    Corresponding authors

    Correspondence to Magdalena Götz or Mark Hübener.

    Extended data

    Extended data figures

    1. 1.

      Lesion model and identity of transplanted neurons.

    2. 2.

      Identity of embryonic neurons before transplantation.

    3. 3.

      Intrinsic signal imaging and location of grafting site, neuron reconstruction, and control for fusion events.

    4. 4.

      Modes of formation of spines and boutons, and long-term survival of grafted neurons.

    5. 5.

      Local and brain-wide monosynaptic input to transplanted neurons.

    6. 6.

      Normal circuitry of upper layer neurons in V1.

    7. 7.

      Quantitative analysis of the monosynaptic synaptic tracing of regenerated and endogenous neuronal circuits.

    8. 8.

      Transplanted neurons in V1 receive topographically organized inputs from the dLGN.

    9. 9.

      Responses to visual stimulation: boutons on the same axon, binocular responses, distribution of preferred directions.

    10. 10.

      Normalized average 2D tuning recorded from example neurons, axons and spines.

    11. 11.

      Orientation and direction selectivity assessed with Gaussian fits.

    Extended data tables

    1. 1.

      Abbreviation list of anatomical areas in the adult mouse brain

    Supplementary information

    Videos

    1. 1.

      Morphological development of a transplanted neuron

      Neuron 3 to 92 dpt (same as in Fig. 1), developing a L2/3 pyramidal cell-like morphology within 3 wpt. Stable overall morphology 4 to 13 wpt. In vivo two-photon z-stacks depicted as maximum projections, time series.

    2. 2.

      Formation of dendritic spines

      Dendrite 6 to 75 dpt, forming first dendritic spines at 9 dpt. Z-stack maximum projections, time series.

    3. 3.

      Formation of axonal boutons

      Axon 5 to 84 dpt (same as in Fig. 2), forming first axonal boutons at 5 dpt, a secondary branch forms at 7 dpt. Z-stack maximum projections, time series.

    4. 4.

      3D reconstruction of dLGN relay cells retrogradely traced in mice with distinct transplantation sites in V1

      Data from each mouse (n=8) is represented with a distinct color, and each sphere corresponds to one neuron (n=3-96/mouse). Animation starts with an anterior view and then rotates around several axes, demonstrating that cells form segregated clusters in specific parts of the dLGN (surface in wireframe; see Extended Data Fig. 8c).

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