A 2022 amphibian study by the Electroceuticals team investigated limb regeneration:

“Organisms such as Xenopus laevis – whose limited regenerative capacities in adulthood mirror those of humans – are important models with which to test interventions that can restore form and function. We demonstrate long-term (18 months) regrowth, marked tissue repatterning, and functional restoration of an amputated X. laevis hindlimb following a 24-hour exposure to a multidrug, pro-regenerative treatment delivered by a wearable bioreactor.

• Regenerated multidrug treatment (MDT) hindlimbs were longer than the no added factors (BD) and no device (ND) groups by 2.5 mpa, as indicated by growth beyond resection site (red dashed line).
• At 4 mpa, vascularized structures developed at the distal extension of MDT (yellow arrow), but not BD or ND regenerates.
• At 9 mpa, digit-like projections appeared (blue arrow), contrasting hypomorphic spikes of BD and ND regenerates (pink arrows).

We suggest that the overall strategy of providing wound cells with an aqueous, amniotic-like environment, which is uniquely given through our bioreactor, that contains pro-regenerative signals is likely to be an effective method for kickstarting biomedically relevant growth and patterning cascades that are too complex to directly implement. One additional direction that may present new opportunities for enhanced regeneration is to assess immune function in relation to tissue remodeling.”

https://www.science.org/doi/10.1126/sciadv.abj2164 “Acute multidrug delivery via a wearable bioreactor facilitates long-term limb regeneration and functional recovery in adult Xenopus laevis”