In vitro efficacy of silk sericin microparticles and platelet lysate for intervertebral disk regeneration.

Intervertebral disk degeneration is an oxidative and inflammatory pathological condition that
induces viability and functionality reduction of Nucleus Pulposus cells (NPs). Cellular therapies
were previously proposed to repair and substitute the herniated disk but low proliferative index and
pathological conditions of NPs dramatically reduced the efficacy of this approach. To overcome
these problems we proposed, for the first time, a therapeutic system based on the association of silk
sericin microparticles and platelet-derived products. Silk sericin (SS) is a bioactive protein with
marked antioxidant properties, while platelet lysate (PL) and platelet poor plasma (PPP) represent a
source of growth factors able to support cell viability and to promote tissue regeneration.
We demonstrated that the mixture PL+PPP promoted NPs proliferation with a significant reduction
of cellular doubling time. SS microparticles, alone or in combination with PPP, presented the higher
ROS-scavenging activity while, SS microparticles and PL resulted as the best association able to
protect NPs against oxidative stress induce by hydroxide peroxide.
Based on these results, the authors are confident that, with the ever increasing need of efficacious
tools for regenerative medicine purposes, SS microparticles and PL+PPP association could
represent an effective approach for the development of low impact and non-invasive therapies.