A novel approach to label bone marrow-derived mesenchymal stem cells with mixed-surface PAMAM dendrimers

Abstract

Background Transplantation of mesenchymal stem cells has created enormous opportunities as a potential treatment for various diseases including neurodegenerative diseases. Given current techniques, such as Hoechst labeling, have safety and leakage issues, our study focused, as a proof-of-concept, on a new dendrimer-based technique for labeling these stem cells to ensure their efficacy and safety following transplantation into the brain of a healthy mice. Methods and results The bone marrow-derived mesenchymal stem cells (BM-MSCs) were labeled using polyaminoamine (PAMAM) dendrimers following which their stemness based on their proliferation and differentiation ability were analyzed by gold standard methods. These labeled BM-MSCs were transplanted into the striatum of C57BL/6J mice and were tracked using in vivo imaging system (IVIS) and analyzed using tissue imaging, 2 weeks after transplantation. Our results showed that the dendrimer-labeled BM-MSCs were able to successfully maintain their stemness and were tracked in vivo following transplantation. Unlike Hoechst, we did not find the dendrimers to be leaking out of the cells and were very specific to the cells that up took the dendrimers. Moreover, no adverse events were found in the transplanted animals proving that this is a safer method. Conclusions Labeling BM-MSCs using fluorescently tagged PAMAM dendrimers can be used as a potentially safe and efficient method for labeling cells, particularly stem cells, in vitro and in vivo following transplantation in rodents.

Polymeric Dendrimers as Nanocarrier Vectors for Neurotheranostics

“…[195] In recent years, several PAMAM dendrimers as nanocarriers for imaging agents have been reported for applicability in CNS diseases diagnosis. [196] The G4 mixed-surface PAMAM dendrimer with low toxicity was designed and synthesized by Munro et al [197] Most of the amine groups (90%) on the exterior of PAMAM dendrimers are replaced by hydroxyl groups, and the reserved amine (10%) is readily fluorescently tagged to provide imaging. This mixed-surface dendrimer labeled with fluorescein could be taken up by neurons and glial cells in vitro and in vivo after local injection.…”

Developments in Treatment Methodologies Using Dendrimers for Infectious Diseases

“…Recently, it was shown that the use of G4 mixed-surface dendrimers, which has 90% of their surface covered with hydroxyl groups and the other 10% with amine groups, can mitigate the problems caused by traditional PAMAM dendrimers. Use of these dendrimers covered with hydroxyl groups can not only help to reduce the cytotoxicity caused by the PAMAM dendrimers but they are easy to fluorescently label and target neuron and glial cells [ 192 ]. Their capability for targeting neuron and glial cells can help them overcome problems caused by traditional PAMAM dendrimers, which is their inability to cross the blood brain barrier (BBB).…”

Recent advances of dendrimer in targeted delivery of drugs and genes to stem cells as cellular vehicles

“…Based on analysis by in vivo imaging systems, the transplanted labeled cells preserved their stemness and were readily traceable in the brain. 87 Functionalizing Fe 3 O 4 using poly (epsilon lysine) dendrons while simultaneously covering them with a polyacrylic acid (PAAMNP) thin layer improved their binding to the cellular glycocalyx. Hence, human bone marrow mesenchymal stem/progenitor cell (BMSC) magnetization can rapidly increase their proliferation and differentiation without notable cytotoxicity.…”

“…In another study, MSCs derived from bone marrow (BM‐MSCs) were marked with either PAMAM dendrimer‐FITC or Cy5.5 and infused to C57BL/6J mice (striatum region). Based on analysis by in vivo imaging systems, the transplanted labeled cells preserved their stemness and were readily traceable in the brain 87 …”