**13. Conclusions**

Much of preclinical studies which employed a diverse range of naturally occurring as well as engineered AAV vectors in the last decade provided ample evidence that therapeutic gene transfer certainly holds a great promise for patients with inherited disorders such as those that developed as a result of blood clotting factor deficiency and mutated retinal genes causing blindness. Moreover, it is now becoming clear that the findings of preclinical studies of noninherited disorders suggest that clinical studies utilizing therapeutic gene transfer is feasible.

Currently active clinical trials in patients with inherited disorders using a diverse range of AAV vector types will be expected to provide valuable insights into the safety and efficacy of AAV vectors [133]. Since the FDA as well as the EU has now endorsed human gene therapy, there is every possibility that the volume of gene therapy research employing next-generation AAV vectors for both inherited and non-inherited disorders in both preclinical and clinical settings would be expected to increase in the coming years. Moreover, a rapidly evolving technology of AAV vector engineering and the use of humanized animal models would be a key for rapid translation of preclinical findings to clinical studies. The findings from our ongoing liver fibrosis/cirrhosis work using human liver-specific AAV-LK-03 vector in humanized FRG mice would be expected to provide valuable information before we commence clinical studies in patients with chronic liver disease.
