Understanding Bioprinting and Its Applications

Understanding Bioprinting and Its Applications Bioprinting, a type of 3D printing,  uses cells and other biological materials as â€Å"inks† to fabricate 3D biological structures. Bioprinted materials have the potential to repair damaged organs, cells, and tissues in the human body. In the future, bioprinting may be used to build entire organs from scratch, a possibility that could transform the field of bioprinting. Materials That Can Be Bioprinted Researchers have studied the bioprinting of many different cell types, including stem cells, muscle cells, and endothelial cells. Several factors determine whether or not a material can be bioprinted. First, the  biological materials must be biocompatible with the materials in the ink and the printer itself. In addition, the mechanical properties of the printed structure, as well as the time it takes for the organ or tissue to mature, also affect the process.   Bioinks typically fall into one of two types: Water-based gels, or hydrogels, act as 3D structures in which cells can thrive. Hydrogels containing cells are printed into defined shapes, and the polymers in the hydrogels are joined together or crosslinked so that the printed gel becomes stronger. These polymers can be naturally derived or synthetic, but should be compatible with the cells.Aggregates of cells that  spontaneously fuse together into tissues after printing. How Bioprinting Works The bioprinting process has many similarities with the 3D printing process. Bioprinting is generally divided into the following steps:   Preprocessing: A 3D model based on a digital reconstruction of the  organ or tissue to be bioprinted is prepared. This reconstruction can be created based on images captured non-invasively (e.g. with an MRI) or through a more invasive process, such as a series of two-dimensional slices imaged with X-rays.     Processing: The tissue or organ based on the 3D model in the preprocessing stage is printed. Like in other types of 3D printing, layers of material are successively added together in order to print the material.Postprocessing: Necessary procedures are performed to transform the print into a functional organ or tissue. These procedures may include placing the print in a special chamber that helps cells to mature properly and more quickly. Types of Bioprinters As with other types of 3D printing, bioinks can be printed several different way.  Each method has its own distinct advantages and disadvantages. Inkjet-based bioprinting acts similarly to an office inkjet printer. When a design is printed with an inkjet printer, ink is fired through many tiny nozzles onto the paper. This creates an image made of many droplets that are so small, they are not visible to the eye. Researchers have adapted inkjet printing for bioprinting, including methods that use heat or vibration to push ink through the nozzles. These bioprinters are more affordable than other techniques, but are limited to low-viscosity bioinks, which could in turn constrain the types of materials that can be printed.Laser-assisted bioprinting uses a laser to move cells from a solution onto a surface with high precision. The laser heats up part of the solution, creating an air pocket and displacing cells towards a surface. Because this technique does not require small nozzles like in inkjet-based bioprinting, higher viscosity materials, which cannot flow easily through nozzles, can be used. Laser-assisted bioprinting also allo ws for very high precision printing. However, the heat from the laser may damage the cells being printed. Furthermore, the technique cannot easily be scaled up to quickly print structures in large quantities. Extrusion-based bioprinting uses pressure to force material out of a nozzle to create fixed shapes. This method is relatively versatile: biomaterials with different viscosities can be printed by adjusting the pressure, though care should be taken as higher pressures are more likely to damage the cells. Extrusion-based bioprinting can likely be scaled up for manufacturing, but may not be as precise as other techniques.Electrospray and electrospinning bioprinters  make use of electric fields to create droplets or fibers, respectively. These methods can have up to nanometer-level precision. However, they utilize very high voltage, which may be unsafe for cells. Applications of Bioprinting Because bioprinting enables the precise construction of biological structures, the technique may find many uses in biomedicine. Researchers have used bioprinting to introduce cells to help repair the heart after a heart attack as well as deposit cells into wounded skin or cartilage.  Bioprinting has been used to fabricate heart valves for possible use in patients with heart disease, build muscle and bone tissues, and help repair nerves. Though more work needs to be done to determine  how these results would perform in a clinical setting, the research shows that bioprinting could be used to help regenerate tissues during surgery or after injury. Bioprinters could, in the future, also enable entire organs like livers or hearts to be made from scratch and used in organ transplants. 4D Bioprinting In addition to 3D bioprinting, some groups have also examined 4D bioprinting, which takes into account the fourth dimension of time. 4D bioprinting  is based on the idea that the printed 3D structures may continue to evolve over time, even after they have been printed. The structures may thus change their shape and/or function when exposed to the right stimulus, like heat. 4D bioprinting may  find use in biomedical areas, such as making blood vessels by taking advantage of how some biological constructs fold and roll. The Future Although bioprinting could help save many lives in the future, a number of challenges have yet to be addressed. For example, the printed structures may be weak and unable to retain their shape after they are transferred to the appropriate location on the body. Furthermore, tissues and organs are complex, containing many different types of cells arranged in very precise ways. Current printing technologies may not be able to replicate such intricate architectures. Finally, existing techniques are also limited to certain types of materials, a limited range of viscosities, and limited precision. Each technique has the potential to cause damage to the cells and other materials being printed. These issues will be addressed as researchers continue to develop bioprinting to tackle increasingly difficult engineering and medical problems. References Beating, pumping heart cells generated using 3D printer could help heart attack patients, Sophie Scott and Rebecca Armitage, ABC.Dababneh, A., and Ozbolat, I. â€Å"Bioprinting technology: A current state-of-the-art review.† Journal of Manufacturing Science and Engineering, 2014, vol. 136, no. 6, doi: 10.1115/1.4028512.Gao, B., Yang, Q., Zhao, X., Jin, G., Ma, Y., and Xu, F. â€Å"4D bioprinting for biomedical applications.† Trends in Biotechnology, 2016, vol. 34, no. 9, pp. 746-756, doi: 10.1016/j.tibtech.2016.03.004.Hong, N., Yang, G., Lee, J., and Kim, G. â€Å"3D bioprinting and its in vivo applications.† Journal of Biomedical Materials Research, 2017, vol. 106, no. 1, doi: 10.1002/jbm.b.33826.Mironov, V., Boland, T., Trusk, T., Forgacs, G., and Markwald, P. â€Å"Organ printing: computer-aided jet-based 3D tissue engineering.† Trends in Biotechnology, 2003, vol. 21, no. 4, pp. 157-161, doi: 10.1016/S0167-7799(03)00033-7.Murphy, S., and Atala, A. †Å"3D bioprinting of tissues and organs.† Nature Biotechnology, 2014, vol. 32, no. 8, pp. 773-785, doi: 10.1038/nbt.2958. Seol, Y., Kang, H., Lee, S., Atala, A., and Yoo, J. Bioprinting technology and its applications. European Journal of Cardio-Thoracic Surgery, 2014, vol. 46, no. 3, pp. 342-348, doi: 10.1093/ejcts/ezu148.Sun, W., and Lal, P. â€Å"Recent development on computer aided tissue engineering – a review.† Computer Methods and Programs in Biomedicine, vol. 67, no. 2, pp. 85-103, doi: 10.1016/S0169-2607(01)00116-X.

Edward and Sarah Bishop of the Salem Witch Trials

Edward and Sarah Bishop of the Salem Witch Trials Edward Bishop and Sarah Bishop were tavern keepers that were arrested, examined, and imprisoned as part of the Salem witch trials of 1692. At the time, Edward was about 44 years old and Sarah Wildes Bishop was about 41 years old. There were three or four Edward Bishops living in the area at that time. This Edward Bishop seems to be the one who was born on April 23, 1648.  However, Sarah Bishops year of birth is not known. Note: Bishop is sometimes spelled Bushop or Besop in the records. Edward is sometimes identified as Edward Bishop Jr. Sarah Wildes Bishop was the stepdaughter of Sarah Averill Wildes who was named as a witch by Deliverance Hobbs and executed on July 19, 1692. Bridget Bishop is usually credited with running a tavern that was something of a town scandal, but it was more likely Sarah and Edward Bishop who ran it out of their home. The Background of Edward and Sarah Edward Bishop may have been the son of Edward Bishop, the husband of Bridget Bishop. Sarah and Edward Bishop were the  parents of twelve children. At the time of the Salem witch trials, an older Edward Bishop also lived in Salem. He and his wife Hannah signed a petition protesting the accusations against Rebecca Nurse.  This Edward Bishop seems to have been the father of the Edward Bishop married to Bridget Bishop, and thus the grandfather of the Edward Bishop married to Sarah Wildes Bishop. Victims of the Salem Witch Trials Edward Bishop and Sarah Bishop were arrested on April 21 of 1692 with Sarahs stepmother Sarah Wildes, William and Deliverance Hobbs, Nehemiah Abbott Jr., Mary Easty, Mary Black and Mary English. Edward and Sarah Bishop were examined on April 22 by magistrates Jonathan Corwin and John Hathorne, on the same day as Sarah Wildes, Mary Easty, Nehemiah Abbott Jr., William and Deliverance Hobbs, Mary Black, and Mary English. Among those who testified against Sarah Bishop was the Rev. John Hale of Beverly. He outlined accusations from a neighbor of the Bishops that she did entertain people in her house at unseasonable hours in the night to keep drinking and playing at shovel-board whereby discord did arise in other families and young people were in danger to be corrupted. The neighbor, Christian Trask, wife of John Trask, had attempted to reprove Sarah Bishop but received no satisfaction from her about it.  Hale stated that Edward Bishops would have been a house if great profaneness and iniquity if the behavior had not been stopped. Edward and Sarah Bishop were found to have committed witchcraft against Ann Putnam Jr., Mercy Lewis, and Abigail Williams. Elizabeth Balch, wife of Benjamin Balch Jr., and her sister, Abigail Walden, also testified against Sarah Bishop, claiming they heard Edward accuse Elizabeth of entertaining Satan at night. Edward and Sarah were jailed in Salem and then in Boston, and their property was seized. They escaped from the Boston jail for a short time. After the Trials After their trial their son, Samuel Bishop recovered their property. In a 1710 affidavit attempting to gain recompense for the damages theyd suffered and to clear their names, Edward Bishop said they were prisnors for thirtiey seven wekes and required to pay ten shillings pur weeake for our bord plus five pounds. The son of Sarah and Edward Bishop Jr., Edward Bishop III, married Susannah Putnam, part of the family who had leveled many of the accusations of witchcraft in 1692. In 1975 David Greene suggested that the Edward Bishop accused - with his wife Sarah - was not related to Bridget Bishop and her husband, Edward Bishop the sawyer, but was the son of another Edward Bishop in town.