Introduction

Biologic mesh development resulted from a search for a biomaterial that could address the problems associated with permanent synthetic mesh, including chronic inflammation and foreign body reaction, stiffness and fibrosis, and mesh infection. Since the introduction of biologic mesh, the market has been rife with new biologic materials attached to largely unsupported claims of superiority and safety. With data comprised mainly from animal studies and Level III evidence, there has been little science regarding these materials, yet surgeons have been using these materials with increasing frequency driving a multi-million dollar market.

Basic science of biologic meshes

Most often derived from human or porcine dermis, these materials have been processed to acellular, porous extracellular matrix scaffolds of collagen and elastin. Some source growth factors remain and attract endothelial cells and subsequent fibroblasts into the mesh. These host cells release additional chemoattractants that signal the migration of other structural cells. The three-dimensional nature of the mesh and porosity allow cells to enter the mesh and adhere. What happens from there is a cycle of remodeling consisting of degradation of the biologic mesh and regeneration of the collagen scaffold with host tissue. The balance of this degradation and rebuilding process, and the speed with which it occurs, influences the ultimate strength and structure of the biologic mesh hernia repair.
The processing of the biologic mesh for production is by and large a proprietary procedure, making it difficult for surgeons to access information and answer several questions about the final products. These uncertain areas include decellularization, the sterilization process, the source of human dermis in terms of donor age and body part, and the crosslinking process. The cells are removed from the grafts in different ways: physical means such as dessication, chemical processes, or enzymatic reactions. Some of the products are terminally sterilized while others are not, resulting in variations in storage and pre-use hydration requirements. Sterilization options include gamma radiation, ethylene oxide, or hydrogen peroxide. Some companies instill chemicals, such as gluteraldehyde, into the biologic graft to induce additional crosslinking bonds in the graft to slow down the degradation process in the hope of leading to a stronger host collagen framework. However, this is a not a natural feature of the donor tissue and there is concern about the lack of remodeling in too heavily crosslinked grafts. This unintended feature could result in a poorly integrated graft and foreign body reaction, similar to some permanent synthetic meshes.
The advantage of crosslinked mesh versus non-crosslinked mesh remains a controversial area. Early investigation at Washington University presented at the 2009World Hernia Congress and the 2010 American Hernia Society Meeting showed increased stiffness for two crosslinked biologic mesh products (porcine dermis and bovine pericardium) compared to the non-crosslinked bovine pericardium mesh. ^1-2 Greater cell infiltration was seen in the non-crosslinked mesh. Future investigation is warranted as to whether these characteristics are clinically important or if the crosslinked mesh poses an increased risk for infection by preventing collagen breakdown and macrophage migration.

Indications for use

The theoretical advantage of biologic mesh over synthetic mesh has appealed to surgeons, mostly in the United States. These meshes are not widely favored nor used in Europe and elsewhere due to the high cost of the biologic mesh over its cheaper and more widely applicable synthetic mesh counterpart. Over the last decade, surgeons have utilized biologic mesh in a variety of cases ranging from primary ventral and inguinal hernia repair in non-infected fields, recurrent hernias, reinforced hernia repair, hernia prophylaxis, and the most widely used application, hernia repair in the contaminated or potentially contaminated field.

Non contaminated setting

The use of biologic mesh in primary or recurrent ventral or inguinal herniorrhaphy in the noncontaminated and previously uninfected field is difficult to justify due to the high material cost without added benefit. There is very little data regarding the performance of biologic mesh in these settings.

Bridging the gap

The poor performance of the mesh in terms of laxity in a bridging repair makes this an unacceptable repair in the noncontaminated setting. Blatnik et al documented a recurrence rate of 80% for bridging repair with acellular dermal matrix at an average cost of $5,100 per patient, comparing the repair to an “expensive hernia sac.”³ The laxity associated with biologic mesh has been documented in other series.⁴

Reinforcement of the repair

The use of allograft or xenograft as reinforcement of a primary ventral hernia repair is felt to be a more sound approach. This fits with what we know of the science of biologic meshes in that placement in well-vascularized tissue is favorable for the ingrowth and remodeling process. Rosen’s group at Case Western investigated this and found a reduction in ventral hernia recurrence rate with a components separation midline repair reinforced with acellular dermal matrix (20%) compared to the 80% recurrence after bridging allograft repair.⁵

Contaminated Setting

The presence of contamination may limit the applicability of permanent synthetic mesh in some hernia repairs. Biologic mesh may be acceptable for this purpose or for placement in open wounds as a staged closure in complex abdominal wall reconstruction. There is limited data in both of these areas, with some noting a high risk of hernia recurrence and associated infection. The data is mostly limited to animal models and case series. ^6,7 However, the lack of suitable alternatives has made biologic mesh attractive for contaminated field hernia repair.

Prophylaxis during stoma creation

The role of biologic mesh has been explored in prevention of parastomal hernias. An ongoing study of human dermis allograft placed at the time of construction of ileal conduits after cystectomy shows promising results with a decreased risk of hernia occurrence (30.4% v. 6.3%).⁸ Biologic mesh has also been used in the treatment of parastomal hernias where infection is a concern.⁹ With increasing reports of prophylactic synthetic mesh placement at the time of ostomy construction, the use of biologic mesh in this preventative setting may decline.

Hiatal Hernias

Biologic mesh has been utilized in the reinforcement of paraesophageal hernia repair. The randomized controlled trial of mesh repair for paraesophageal hernia lead by Oelschlager is the only Level I human study of biologic mesh.¹⁰ This study showed a decreased risk of hernia recurrence with mesh repair, from 24% to 9%. The recommendation for mesh reinforced hiatal repair is made with some caution; significant mesh complications, ranging from mesh erosion to esophageal stenosis and fibrosis, were documented in a follow-up study^.11

Conclusion

In summary, biologic grafts represent a major advancement in complex hernia repair. Further investigation regarding the appropriate indications, performance of the grafts based on individual properties such as crosslinking, and potential complications is needed. Given the high cost of most of these materials and the limited available data, biologic mesh should be used judiciously and only when permanent synthetic mesh is inappropriate, such as in the contaminated field. The FDA reported complications of these materials warrant caution and sound surgical judgment.12,13

Biologic/bioresorbable graft comparison

References

1. Melman L et al. Proceedings of World Hernia Congress. Berlin, Germany. 2009
2. Melman L et al. Histologic Evaluation of Crosslinked and Non-crosslinked Biologic Mesh Materials in a Porcine Model of Mature Ventral Incisional Hernia Repair. Proceedings of American Hernia Society: Hernia Repair 2010. Orlando, FL. 2010
3. Blatnik J, Jin J, Rosen M. Abdominal hernia repair with bridging acellular dermal matrix–an expensive hernia sac. Am J Surg. 2008 Jul;196(1):47-5
4. Bluebond-Langner R, Keifa ES, Mithani S, Bochicchio GV, Scalea T, Rodriguez ED. Recurrent abdominal laxity following interpositional human acellular dermal matrix. Ann Plast Surg. 2008 Jan;60(1):76-80.
5. Jin J, Rosen MJ, Blatnik J, McGee MF, Williams CP, Marks J, Ponsky J. Use of acellular dermal matrix for complicated ventral hernia repair: does technique affect outcomes? J Am Coll Surg. 2007 Nov;205(5):654-60.
6. Saettele TM, Bachman SL, Costello CR, Grant SA, Cleveland DS, Loy TS, Kolder DG, Ramshaw BJ. Use of porcine dermal collagen as a prosthetic mesh in a contaminated field for ventral hernia repair: a case report. Hernia. 2007 Jun;11(3):279-85.
7. Candage R, Jones K, Luchette FA, Sinacore JM, Vandevender D, Reed RL 2nd. Use of human acellular dermal matrix for hernia repair: friend or foe? Surgery. 2008 Oct;144(4):703-9.
8. Harold KL, et al. Early Results of a Prospective Randomized Study Using Acellular Human Dermal Matrix (Alloderm) to Prevent Parastomal Herniation. Proceedings of American Hernia Society: Hernia Repair 2010. Orlando, FL. 2010
9. Lo Menzo E, Martinez JM, Spector SA, Iglesias A, Degennaro V, Cappellani A. Use of biologic mesh for a complicated paracolostomy hernia. Am J Surg. 2008 Nov;196(5):715-9.
10. Oelschlager BK, Pellegrini CA, Hunter J, Soper N, Brunt M, Sheppard B, Jobe B, Polissar N, Mitsumori L, Nelson J, Swanstrom L. Biologic prosthesis reduces recurrence after laparoscopic paraesophageal hernia repair: a multicenter, prospective, randomized trial. Ann Surg. 2006 Oct;244(4):481-90.
11. Stadlhuber RJ, Sherif AE, Mittal SK, Fitzgibbons RJ Jr, Michael Brunt L, Hunter JG, Demeester TR, Swanstrom LL, Daniel Smith C, Filipi CJ. Mesh complications after prosthetic reinforcement of hiatal closure: a 28-case series. Surg Endosc. 2009 Jun;23(6):1219-26.
12. Rosen MJ. Biologic mesh for abdominal wall reconstruction: a critical appraisal. Am Surg. 2010 Jan;76(1):1-6.
13. Harth KC, Rosen MJ. Major complications associated with xenograft biologic mesh implantation in abdominal wall reconstruction. Surg Innov. 2009 Dec;16(4):324-9.
14. Gina Adrales, M.D. Biological Meshes – Indications and Shortcomings. Challenging Hernias Post-Graduate Course. 12thWorld Congress of Endoscopic Surgery. April 15, 2010

Link to: Use of synthetic mesh in the infected field