**11. Conclusion**

In conclusion, for development of safe and efficient non-viral vector systems a lot of investigations are needed before enter clinical trials. In our book chapter we mainly focused on PEI-related polymers for siRNA delivery to the lungs and gave an overview of the ongoing research in this field with a great focus on toxicity. To improve the toxicity profile of such carriers for pulmonary application one of the biggest challenge is to overcome the inflammatory response besides reduction of the overall cytotoxicity. Future studies should implement basic toxicity testing like evaluation of cytotoxicity (cell viability, LDH release, erythrocytes aggregation, apoptosis), inflammation (cytokine release, gene regulation, in vivo analysis of relevant tissues and cells or liquids), oxidative stress (lipid mediators, GSH levels) before extensively improving the efficacy of such carriers.

### **12. References**


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MacLachlan, I. (2008). Misinterpreting the therapeutic effects of small interfering

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microscopy for the characterisation of nanoscale drug delivery systems. *Eur J Pharm* 


**21** 

*China* 

**PAMAM Dendrimer as Potential Delivery** 

**System for Combined Chemotherapeutic** 

Xuan Zhou, Yu Ren, Xubo Yuan, Peiyu Pu and Chunsheng Kang

*Tianjin research center of basic medical science, Tianjin medical university* 

*Department of Neurosurgery, Laboratory of Neuro-Oncology, Tianjin Medical University* 

Chemotherapeutic drugs are fundamental in cancer management and are responsible for most cases of adjuvant treatment in patients after surgical procedures. However, the median overall survival does not increase in patients treated by concurrent chemo-radiotherapy. Consequently, further studies that could enhance the therapeutic effect should be

Although the biological functions of microRNAs (miRNA) are not completely revealed, there is growing evidence that miRNA pathways are a new mechanism of gene regulation in both normal and diseased conditions [2]. Recent evidence has shown that miRNA mutations or aberrant expression patterns correlate with various diseases, such as cancer, viral infections, cardiovascular and indicates that miRNAs can function as tumor suppressors and oncogenes and oretically become a target to enhance the chemotherapeutic effect in

However, although much work has been accomplished, the development of an efficient delivery system still remain a major challenge for the wide application of miRNA. In the following sections -- after a brief introduction of the miRNA strategies -- the potential and contributions of dendrimers in the development of effective non-viral delivery systems for

MicroRNAs (miRNAs) are a class of naturally occurring small non-coding RNAs, approximately 22 nucleotides in length, that target protein-coding mRNAs at the posttranscriptional level [4]. Generally, mature miRNAs are integrated into a protein–RNA complex called a microRNA RNPs (similar to the RISCs (RNA-induced silencing complexes) for siRNA). miRNAs bind through partial sequence homology to the 3\_-untranslated regions (3'-UTRs) of target genes. Because of this unique feature, a single miRNA has

combined the microRNA therapy with drug delivery will be discussed.

**1. Introduction** 

encouraged [1].

cancer therapy.

**2. MicroRNA strategy** 

**and MicroRNA-21 Gene Therapy** 

*Tianjin Medical University Cancer Institute & Hospital School of Materials Science & Engineering, Tianjin University* 

*First Department of Head and Neck Cancer* 

