Graphite Bio, a CIRM-catalyzed spinout from Stanford University that launched just 14 months ago has now filed the official SEC paperwork for an initial public offering (IPO). The company was formed by CIRM-funded researchers Matt Porteus, M.D., Ph.D. and Maria Grazia Roncarolo, M.D.
Six years ago, Dr. Porteus and Dr. Roncarolo, in conjunction with Stanford University, received a CIRM grant of approximately $875K to develop a method to use CRISPR gene editing technology to correct the blood stem cells of infants with X-linked severe combined immunodeficiency (X-SCID), a genetic condition that results in a weakened immune system unable to fight the slightest infection.
Recently, Dr. Porteus, in conjunction with Graphite, received a CIRM grant of approximately $4.85M to apply the CRISPR gene editing approach to correct the blood stem cells of patients with sickle cell disease, a condition that causes “sickle” shaped red blood cells. As a result of this shape, the cells clump together and clog up blood vessels, causing intense pain, damaging organs, and increasing the risk of strokes and premature death. The condition disproportionately affects members of the Black and Latin communities.
CIRM funding helped Stanford complete the preclinical development of the sickle cell disease gene therapy and it enabled Graphite to file an Investigational New Drug (IND) application with the U.S. Food and Drug Administration (FDA), one of the last steps necessary before conducting a human clinical trial of a potential therapy. Towards the end of 2020, Graphite got the green light from the FDA to conduct a trial using the gene therapy in patients with sickle cell disease.
In a San Francisco Business Times report, Graphite CEO Josh Lehrer stated that the company’s goal is to create a platform that can apply a one-time gene therapy for a broad range of genetic diseases.
The Stem Cellar 
All complex eukaryotes or higher organisms contain exon and intron sequences in their genomic structure. Exon sequences are the active coding parts of the genome but introns do not code for functioning proteins. The amount of total introns varies in different species and the length of the introns is varying in different genes, even within the same species genome. In complex multicellular organisms (such as plants and vertebrates), introns are about 10- fold longer than the exons. In human, introns sequences constitute ~25% of genome which is 4-5 times the size of exons. However, intron is not seen in simple prokaryotes and eukaryotes( such as fungi and protozoa).
During the cells proliferation, all introns are copied into RNA by transcription and DNA by replication processes but intron sequences do not participate in protein-coding sequences. Thus, introns are eliminated by a complex molecular machinery called alternative spliceosome. The splicing event plays important role to control molecular mechanism of producing multiple variant proteins from a single gene in the genome of eukaryote cell. Therefore, the advantages of introns include the possibility to create new genes by cutting and pasting exons from existing gene in the genome or to diversify the proteins output of single gene in genome by splicing the exons together in different ways. Evidence suggested that ~95% of multiexon genes in the human genome may undergo alternative splicing. In addition, introns are essential to increase gene expression, transcription rate of RNA and stability of transcript in nuclear before exporting to cytoplasm. The splicing event occurs in the nucleus of cell before the mature and functional RNAs (mRNA) are produced and migrated to cytoplasm. Therefore, introns participate in critical roles in regulation of transcription and genomic organization.
Therefore, those mRNAs from an organism or from specific cells of an organism are extract to produce complementary DNA (cDNA) which are prepared by extraction and multistep reaction of catalyging enzyme reverse transcriptase. Those functional genes without containing introns had been taken from cDNA library to study inheritant disease of organisms caused by mutations.
In case of genomic library (not a cDNA library) contains DNA fragments that represent the entire genome of an organism. It is difficult to study the expression of gene in prokaryote system taken from genomic library due to lack of introns to process splicing.
The current technology of CRISPR editing approach to correct the defective gene in blood stem cells of human genetic disorders may cause more harm than benefit to patients’ health and lives. The human genomic sequences contain different sizes and copy numbers of intron which may cause the CRISPR can easily off-target. The reading frame of a gene in genomic sequence is not entirely similar to cDNA. Human genomic DNA contains more introns and in varying sizes may shut off the efficiency of CRISPR approach. Unless a functional gene is in coincident has similar DNA sequence to human genomic DNA, CRISPR editing approach is highly efficient and recommended to treat that human genetic disorder.