Preface

 For conventional genetic cloning, target genes are cleaved at restriction sites using restriction endonucleases. Researchers cannot modify genomic sites and it usually takes a lot of work, time, and patience to make and screen for desired clones. Current gene-editing technologies, including ZFNs, TALENs, and CRISPRs/ Cas9, can be utilized to engineer the genes of interest in living organisms with unprecedented efficiency and precision, without the limitation of restriction site availability. Specific and efficient genomic engineering has been performed in human cells, microbes, plants, animals, etc. at will. Additionally, it has been applied in manufacturing products, including testing tools, agricultural products, foods, industrial products, medicinal products, etc. Among them, novel therapeutic strategies based on gene-editing technologies are expected to bring hope for patient recovery from serious diseases for which there are still no effective drugs or medical devices available.

Many biotechnology companies have successfully produced nonhuman therapeutic products and medicinal products using gene-editing technologies. More and more products are being developed and approved for sale. Consequently, many enterprises are encouraged to become involved in manufacturing products based on these technologies because of their perspectives for multiple applications. For example, CRISPR has become an industry that is developing prosperously. These enterprises also promote industry innovation through the transfer of technologies and collaboration between academia and industry.

Gene-editing technologies are still being discovered and are expected to become more mature, specific, efficient, and secure for applications in the near future. The potential benefits of these revolutionary technologies are endless. However, like any powerful tool, there are also associated challenges, including safety and ethical/moral concerns, that need to be considered. Research and ethical guidelines from national and international organizations will be critical for funding agencies and institutional review boards to regulate these technologies, especially in the gene editing of human germ line cells and embryos. The aim is to maximize the benefits and minimize the possible risks of gene-editing technologies.

We wish all current and future research work, including the discovery, applications, perspectives, and challenges of gene-editing technologies, to have a worthwhile impact on the betterment of human health. It is hoped that all perspectives will become realities and any challenges will be overcome provided that academia, industry, governments, and international societies constantly endeavor and cooperate with each other. Finally, we are grateful for all authors'

participation and IntechOpen's enthusiasm in helping us to complete and publish this book.

### **Yuan-Chuan Chen, PhD**

Program in Comparative Biochemistry, University of California, Berkeley, CA, USA

### **Shiu-Jau Chen, MD, PhD**

Department of Neurosurgery, Mackay Memorial Hospital, Taipei, Taiwan
