Here at Fight Aging! the most recent update on protofection, a possible basis for a way to replace damaged mitochondrial DNA (mtDNA) and remove its contribution to degenerative aging, was late last year. Since the first publication on protofection back in 2005 a number of other potential mechanisms for mitochondrial DNA repair or replacement have emerged, but none of these, protofection included, are moving as rapidly as would be liked. One problem is the regulatory environment in the biggest markets: you are only allowed to develop commercial therapies for named diseases, not for aging, and comparatively few people suffer from named diseases that involve specific, characteristic forms of mitochondrial mutation - as opposed to the general stochastic damage of aging. So there is little funding, and it's actually effectively illegal to try to treat aging this way, despite the great possibilities of this research.
One of the potential target diseases is Leber's hereditary optic neuropathy (LHON), and if you have a good memory you might recall that one of the researchers involved in work on the SENS approach to mitochondrial DNA damage - move the vulnerable genes into the cell nucleus to create a secondary source of the necessary proteins - is primarily concerned with LHON rather than aging.
Here is an open access paper on the use of protofection (among other options) as a LHON therapy, which is also of general interest to anyone looking at this sort of approach to mitochondrial gene therapy for aging or other conditions:
An optimal cure [for LHON] would be gene therapy, which involves introducing the missing gene(s) into the mitochondria to complement the defect. Our recent research results indicate the feasibility of an innovative protein-transduction ("protofection") technology, consisting of a recombinant mitochondrial transcription factor A (TFAM) that avidly binds mtDNA and permits efficient targeting into mitochondria in situ and in vivo. Thus, the development of gene therapy for treating mitochondrial disease offers promise, because it may circumvent the clinical abnormalities and the current inability to treat individual disorders in affected individuals.
We successfully demonstrated introduction of labeled rhTFAM and healthy mtDNA complexed with rhTFAM into homoplasmic LHON cybrid cells containing the G11778A mutation. [Further] results in LHON cybrid cells, demonstrated an increase in mitochondrial genome replication, transcription, translation, and respiration initiated within a week when the complex was introduced into the mitochondria. We also observed the activation of the mitochondrial biogenesis (creation of new mitochondria) program in these human LHON cybrid cells. [It] is expected that this mitochondrial genome manipulation approach based on introduction of exogenous normal or pathogenic mtDNA provides hope for LHON patients afflicted with other mutations in the mitochondrial genome.
The current studies indicate that the mitochondrial genome can be manipulated and lead to improvement in mitochondrial function in in vitro and in vivo models. Future coordinated efforts between scientists and clinicians are necessary to translate these findings towards development of therapies for LHON patients.
This is far from a niche study, despite being related to a niche disease; mitochondrial DNA damage arguably causes a fairly large fraction of degenerative aging. It is incredible to think that regulators actively work to prevent greater funding and more work on this and other items that could help to reverse the effects of aging in the old.