Skin cell gun
The skin cell gun, also known as the skin gun or SkinGun™, is a medical device that sprays a patient's own self-donated (autologous) stem cells to treat burns and other wounds. The skin gun is used in conjunction with a technique that isolates adult stem cells from a postage stamp-sized sample of the patient's own skin for application to the wound site, where they differentiate into normal skin. This treatment can replace conventional methods of treating severe wounds, such as skin grafting. Studies demonstrate that damaged skin tissue regenerates after skin gun treatment significantly more quickly than after traditional treatment methods.   
The skin gun, along with related cell isolation methodologies, were acquired by RenovaCare, Inc. in 2013. The company continues to develop the technology and treatment protocol for commercial distribution, under the brand names SkinGun™ and CellMist™ System respectively. RenovaCare is also exploring opportunities to apply its SkinGun™ treatments to additional indications, including chronic wounds, pigmentation disorders, and cosmetic applications. 
Stem cells from a postage stamp-sized sample of the patient's healthy skin are isolated using a enzymatic tissue processing protocol. The resulting cell suspension is then transferred to a sterile syringe, which is then inserted into the skin gun. Using its unique spray mechanism, the gun uniformly distributes cells directly into the wound. The newly introduced stem cells begin to migrate, multiply, and differentiate, creating new skin tissue in a matter of days.
The entire process – from collecting the skin sample, processing it into a cell suspension, and using the skin gun to spray the stem cells – takes approximately 1.5–2 hours from start to finish. Full re-epithelialization can occur in as little as four days, and after a few months the skin will regain its color and texture.
Early experimental versions of the device were developed by Dr. Jörg Gerlach and StemCell Systems GmbH in Berlin, Germany. Dr. Gerlach and SCS had already developed cell culture bioreactors for culturing useable liver and other solid organ tissues from stem cells, and were seeking a similar platform to culture living skin. They soon discovered that, compared to other organs, the skin is a special case. A skin wound is itself an accessible environment that provides excellent conditions to culture new skin tissue in vivo. This solves the problems of wait times and special challenges in transplanting delicate, cultured tissue inherent to in vitro skin culture technologies.
Researchers developed novel stem cell isolation techniques that maximize stem cell availability for transplantation. To ensure minimal loss in transplanting the isolated cells, engineers at StemCell Systems designed a deposition device, the skin gun, to gently deliver the cell suspension without exposing cells to harsh forces in conventional spray devices.
The skin gun method was first used experimentally at Charité – Universitätsmedizin Berlin on a group of nineteen patients. The clinician in that study determined that the results from the skin gun treatment was so significantly better than traditional grafting that he discontinued performing skin grafts on a control group on the basis of medical ethics.
Biological Basis of Wound Healing
After an abrasion, cut, burn, or other injury, the body uses several different of biological processes to repair the skin. Wound healing generally has three different stages: the inflammatory stage, the proliferative stage and the remodeling stage.
Once the skin is damaged, a series of interrelated events take place in close succession in order to repair the skin. Within minutes after an injury occurs, blood platelets collect at the site of injury to form a clot. This clot limits bleeding at the injury site.
The inflammatory phase involves increased white blood cell activity, removing bacteria and debris from the wound. Biochemical signals instruct regenerative cells to begin dividing, to create new skin tissues much more rapidly than normal.
The proliferative phase is marked by the formation of new skin tissue at the injury site and the general shrinking and eventual disappearance of the wound. New blood vessels are also established during the healing process. The wound is made smaller by myofibroblasts, which hold on to the edges of the wound and slowly get smaller by a system similar to the contraction of muscle cells.
During the remodeling phase, the skin acquires it permanent texture and unneeded cells are disposed of through apoptosis.
Comparison to traditional methods
Whereas it takes mere hours to prepare and administer stem cells with the stem cell gun, it takes 2–3 weeks to produce a skin sheet and harvest it from an external lab. Once the skin sheet has been attached to the wound, blisters form under the newly attached skin, pushing the sheet up, damaging the wound and increasing the risk of infection. The skin gun applies its stem cells directly to the patient's cells, which alleviates the concern of further tissue damage. The artificial vascular system network also provides a reliable source of protection to the skin stem cells. After the wound has been treated, it takes months for the skin sheet to heal over, yet only days for the skin gun to fulfill its function. Reducing the fragility of the cells and time frame of the operation by cleverly employing differentiated stem skin cells in such a way that offers a renewable source of replacement is an essential component of the skin gun’s capability.
To date skin gun treatment has been used exclusively with second degree burns, though there is strong evidence that the treatment will be successful in treating a variety of skin wounds and skin disorders. Patients with infected wounds or with delay in wound healing are suitable for cell grafting treatment. Third-degree burns, however, completely deprive victims of both their epidermis and dermis skin levels, which exposes the tissue surrounding the muscles. The skin gun has not progressed to the point where it can be used for such advanced wounds, and these patients must seek more traditional treatment methods. The skin gun is generally not used for burn victims with anything less than a second-degree burn either. First degree-burns still maintain portions of the epidermis and can readily heal on their own, thus they do not need this expensive technology.
Currently, the skin gun's applications have not been extended to include the regeneration of skin lost due to other injuries or skin diseases. It is also limited in that it is only effective immediately following the burn incident.
Since 2008 the skin gun has been under development for the treatment of second degree burns. It is not yet approved by the FDA. Stem cell damage during the spraying procedure is a current research hurdle. This treatment is only for recently burned victims; it will not yet work for those who suffered the injury a few months prior.
A few days are required for the wounds to internally heal with this new process; but after those few days, the wound still looks damaged. The skin will not start to look as it did before the injury until months afterward. Because pigment cells are so much deeper in the part of the skin than keratinocytes are, pigment cells need much more time to develop.
Benefits and side effects
Traditional skin grafting can be risky, in that chances for infection are relatively high. The skin gun alleviates this concern because the increased speed in which the wound heals directly correlates to the decreased time the wound can be vulnerable to infection. Because of the rapid re-epithelialization associated with skin gun treatment, harmful side effects that can result from an open wound are significantly reduced.  Applying the skin cells is quick and doesn't harm the patient because only a thin layer of the patients’ healthy skin is extracted from the body into the aqueous spray. The electronic spray distributes the skin cells uniformly without damaging the skin cells, and patients feel as if they are sprayed with salt water.
Because the skin cells are actually the patient’s own cells, the skin that is regenerated looks more natural than skin grown from traditional methods. During recovery, the skin cells grow into fully functional layers of the skin, including the dermis, epidermis, and blood vessels. The regenerated skin leaves little scarring. The basic idea of optimizing regenerative healing techniques to damaged biological structures demonstrated by the skin gun in the future may also be applied to engineering reconstruction of vital organs, such as the heart and kidneys.
There are major limitations: the method will not work on deep burns that go through bone and muscle, specifically below the dermis. As of 2011, only several dozen patients have been treated; it remains an experimental, not a proven, method. As of 2011, the skin gun was still in its prototyping stage, since it has only treated a dozen patients in Germany and the US, compared to over 50,000 treated with Dermagraft bioengineered skin substitute. There is thus a lack of published peer reviewed clinical evidence, and no knowledge of long-term stability of the newly generated skin.
In Popular Culture
The skin gun has been featured in numerous books and television shows, including the following examples.
- National Geographic Explorer produced a segment on the skin gun's use in burn treatments, and featured a patient who was released from hospital four days after treatment. This segment first aired on February 7, 2011.
- Tony Robbins discusses skin gun technology in his 2014 book, "Money, Master the Game: 7 Steps to Financial Freedom". 
- The skin gun is featured in DHO Health Science, 8th edition, a 2014 textbook by Louise Simmers, RN.
- Robin L. Smith, MD discusses the skin gun along with other stem cell regenerative therapies in the 2013 book, "The Healing Cell: How the Greatest Revolution in Medical History is Changing Your Life".
- Popular Science magazine's July 2008 issue discusses the skin gun in an article about new medical technologies in a military context.
- Hartmann B., et al. Sprayed cultured epithelial autografts for deep dermal burns of the face and neck. Ann Plast Surg. 2007 Jan;58(1):70-3. (link retrieved Feb 4, 2015)
- Gerlach, J. C. et al. Method for autologous single skin cell isolation for regenerative cell spray transplantation with non-cultured cells. Int J Artif Organs 2011; 34(3): 271 - 279 (link retrieved Feb 4, 2015)
- Gerlach, J. C. et al. Autologous skin cell spray-transplantation for a deep dermal burn patient in an ambulant treatment room setting. Burns 37, e19-e23 (2011) (link retrieved Feb 4, 2015)
- RenovaCare, Inc. (formerly Janus Resources, Inc.) SEC form 8-K/A filed on November 21, 2013.. (link retrieved Feb 4, 2015)
- RenovaCare, Inc. Website Technology Q&A (link retrieved Feb 4, 2015)
- Ellis, Bob (3 Feb 2011). "Skin Gun Uses Adult Stem Cells". Dakota Voice. Retrieved 20 April 2011.
- Lorianna De Giorgio, "Skin gun that sprays stem cells being used on burn victims", Toronto Star, February 7, 2011
- RenovaCareInc.com 'About' page(link retrieved Feb 10, 2015)
- Gerlach, Johnen et al. Method for autologous single skin cell isolation for regenerative cell spray transplantation with non-cultured cells. Int J Artif Organs. 2011 Mar;34(3):271-9.
- Nguyen, D.T., Orgill D.P., Murphy G.F. (2009).The Pathophysiologic Basis for Wound Healing and Cutaneous Regeneration. New York pg. 234 .
- Quinn, J.V. . Tissue Adhesives in Wound Care. B.C. Decker. Hamilton Decker Inc., Ont. B.C. ,1998
- Stadelmann, WK; Digenis, AG; Tobin, GR . "Physiology and healing dynamics of chronic cutaneous wounds.". American journal of surgery 1998. pg 176
- N/A Biomaterials For Treating Skin Loss. Woodhead Publishing (UK/Europe) & CRC Press (US), Cambridge/Boca Raton, pg 25-57.
- "Skin gun sprays stem cells for fast recovery from serious burns." RobAid, February 6, 2011. Accessed March 26, 2011. 
- Edwards 2011
- RobAid 2011
- Scott & White Healthcare, “Second-Degree Burn” “Second-Degree Burn”
- Hanlon, Tegan. "Skin-cell Gun Expedites Burn Victim Recovery Time." The Pitt News (Pittsburgh), February 2, 2011. Accessed March 29, 2011. 
- Underwood, Anne. "Military Medicine: The War on Wounds - Newsweek." Newsweek. 10 May 2008. Web. 10 May 2011. .
- Skin Gun segment video, nationalgeographic.com.
- Robbins, Tony, Money, Master the Game: 7 Steps to Financial Freedom, Simon & Schuster, New York, 2014, pp. 551-2.
- Simmers, L, et al., DHO Health Sciences, 8th ed., Cenage Learning, Stamford, CT, 2014, p 518.
- Smith, R., et al., The Healing Cell: How the Greatest Revolution in Medical History is Changing Your Life, Center Street Publishing, 2013.
- "Rebuilding the Troops", Popular Science, July 2008, p. 29.