How does DMSO act as a carrier for transdermal transport of large molecules? DMSO.org claims the following:  


  "[DMSO] is more successful ferrying some drugs, such as morphine
  sulfate, penicillin, steroids, and cortisone, than others, such as
  insulin."


All of these drugs that it is said to carry are much larger than a single DMSO molecule.  

So what is the general mechanism by which DMSO can bring these relatively high-molecular weight compounds into your body transdermally, where they would not do so otherwise?  Does it simply “wrap them up” in a large complex, or does it possibly just complex the portions of the other compound that prevent it from crossing transdermally?  What is it about insulin for example that prevents it from being carried through the skin?

A quick internet search will give pages of documents basically saying “this is what it does”  but I’ve never found a remotely technical explanation of how this works, particularly for large molecules.  That’s what I’m asking here.  

NOTE 1: I have never used DMSO medicinally and currently have no intentions of doing so.
NOTE 2: I hope this is not considered a duplicate of this question as the answer is specific to the transport of small molecules.
Quote taken from the review (1) (and which is also duplicated in Jacob's 2015 "canonical DMSO" book (2, p. 16)):


  There is some evidence to suggest that DMSO can increase diffusion
  through the 
  stratum corneum by disruption of the barrier function. This probably occurs through aprotic interactions with intercellular lipids and may
  also include reversible distortion of lipid head groups that produce a
  more permeable packing arrangement.  DMSO may also play a role in
  partitioning as well by forming solvent microenvironments within the
  tissue that can effectively extract solute from vehicle. Finally, DMSO
  can have a profound solubilizing effect on less soluble agents in a
  variety of vehicles, increasing penetration simply by delivering a
  higher concentration to the membrane barrier.


alongside with extensive molecular modelling by Gurtovenko in 2007 (3) are both suggesting quick pore formation and expansion alongside with the thinning of cellular membranes:


  The reported membrane thinning and, in particular, pore formation
  provide a credible molecular-level explanation of how DMSO promotes
  permeation of molecules, particularly those of hydrophilic nature,
  through lipid membranes as observed experimentally.


From what I understand, DMSO paves the way for bigger molecules, such as steroids, making inner skin layers and underlying tissue reversibly accessible, sometimes even on nanoscale level. For the precise mechanism I think it is worth reading through the entire paper (3).



(1) Capriotti, K.; Capriotti, J. A. The Journal of clinical and aesthetic dermatology 2012, 5 (9), 24.
(2) Jacob, S. W.; Jack, C. Dimethyl sulfoxide (DMSO) in trauma and disease; CRC Press, 2015.
(3) Gurtovenko, A. A.; Anwar, J. The Journal of Physical Chemistry B 2007, 111 (35), 10453–10460. DOI 10.1021/jp073113e