The single cell as a tool for genetic testing: credibility, precision, implication

Pre-implantation genetic diagnosis-should we use ICSI for all?

OBJECTIVE

Intracytoplasmic sperm injection (ICSI) is commonly used during pre-implantation genetic diagnosis (PGD) in vitro fertilization (IVF), aiming to eliminate the risk of contamination from extraneous sperm DNA. Recently, ICSI "overuse" in non-male infertility has been doubted, since it does not offer an advantage over IVF. Prompted by the aforementioned observations, we sought to assess the accuracy of IVF vs ICSI in PGD cases, as might be reflected by a difference in the prevalence of discarded embryos as a consequent of parental contamination.

METHODS

Cohort-historical study of all consecutive patients admitted to the IVF-PGD program in a large tertiary center. The percentages of complete, incomplete diagnosis, PCR failure, abnormal embryos, and the contamination rate with paternal DNA in the IVF-only and the ICSI-only groups. We reviewed the computerized files of all consecutive women admitted to our IVF for a PGD-PCR cycle. Patients were divided accordingly into three groups: an IVF group-where all the oocytes underwent IVF only, an ICSI group-where all oocytes underwent ICSI, and a mixed group-where sibling oocytes underwent both IVF and ICSI. The laboratory data and the genetic diagnostic results were collected and compared between the different insemination groups.

RESULTS

Nine-hundred and twenty-seven patients underwent IVF-PGD cycles in our program, 315 in the IVF group, 565 in the ICSI group, and 47 in the mixed group. No differences were observed in fertilization rates, the percentage of embryos available for biopsy, and the percentages of complete, incomplete diagnosis, PCR failure, or abnormal embryos, between the IVF-only and the ICSI-only groups and between the IVF and the ICSI of sibling oocytes in the mixed group. Moreover, contamination with paternal DNA, through contamination with sperm cells, was negligible. Not one single case of misdiagnosis was encountered during the study period.

CONCLUSION

It might be therefore concluded that IVF should be the preferred insemination methods in PGD cycles, and ICSI should be indicated only in cases of male-factor infertility.

A simple microfluidic dispenser for single-microparticle and cell samples

Non-destructive isolation of single-cells has become an important need for many biology research laboratories; however, there is a lack of easily employed and inexpensive tools. Here, we present a single-particle sample delivery approach fabricated from simple, economical components that may address this need. In this, we employ unique flow and timing strategies to bridge the significant force and length scale differences inherent in transitioning from single particle isolation to delivery. Demonstrating this approach, we use an optical trap to isolate individual microparticles and red blood cells that are dispensed within separate 50 μl droplets off a microfluidic chip for collection into microscope slides or microtiter plates.

A thematic review of scientific and family interests in Canavan Disease: where are the developmentalists?

BACKGROUND

Canavan Disease is a degenerative neurological condition resulting in a spongy deterioration of the brain. Much research has been conducted by the medical community regarding this condition, but little research can be found in the psychological literature.

METHOD

A review of the scientific literature related to Canavan Disease using the Psychinfo and PubMed databases was conducted covering a 5-year span from 2006 through 2011. Concurrently, a review of parent initiated topics found on the most popular Canavan Disease Internet discussion board was conducted for comparison purposes.

RESULTS

When comparing the topics discussed and information sought among parents with the themes noted in the extant scientific literature, researchers found an exceedingly small overlap between the two communities of interest. In the scientific literature, published research on Canavan Disease focused on three areas: the biochemistry of Canavan Disease, diagnosis and genetic counselling, and clinical therapeutic approaches in Canavan Disease. Of the 42 unique topics raised on a popular Internet discussion board, however, only three (7%) fell into the category of diagnosis and genetic counselling, none (0%) fell into the category of the biochemistry of Canavan Disease, and four fell into the category of clinical therapeutic approaches in Canavan Disease (10%). Of the four posts addressing clinical therapeutic approaches to Canavan Disease, only one post truly overlapped with the topics addressed by the scientific community. Worded differently, while these three categories comprise 100% of the extant scientific literature regarding Canavan Disease, they comprise only 17% of the parent-raised topics. The remaining 83% of parent-raised topics addressed concerns not currently being focusing upon by the scientific community, namely, non-medical practical issues, information regarding specific characteristics of Canavan Disease, non-medical developmental and quality of life issues, and day-to-day developmental and medical concerns.

CONCLUSION

By comparing the extant literature on Canavan Disease with the topics of interest raised by parents and caregivers, it seems clear that there is a significant 'underlap' of topics raised by these two communities of interest, one that may reflect a lack of sensitivity on the part of the scientific community to meet the needs of this population of knowledge seekers. It is the suggestion of these authors that developmental psychology may be the appropriate scientific field within which to address this need and fill this gap in the current literature.

Single-cell isolation using a DVD optical pickup

A low-cost single-cell isolation system incorporating a digital versatile disc burner (DVD RW) optical pickup has been developed. We show that these readily available modules have the required laser power and focusing optics to provide a steady Gaussian beam capable of optically trapping micron-sized colloids and red blood cells. Utility of the pickup is demonstrated through the non-destructive isolation of such particles in a laminar-flow based microfluidic device that captures and translates single microscale objects across streamlines into designated channel exits. In this, the integrated objective lens focusing coils are used to steer the optical trap across the channel, resulting in the isolation of colloids and red blood cells using a very inexpensive off-the-shelf optical component.