Wound healing is a dynamic process that involves a coordinated umoral response of many cell types representing distinct tissue compartments and is fundamentally similar among tissue types. The inflammatory phase of wound healing is characterized by the infiltration of neutrophils, macrophages, and lymphocytes, which participate by releasing pro-inflammatory and anti-inflammatory cytokines, growth factor, ingesting foreign materials, increasing vascular permeability, and promoting fibroblast activity [7, 8]. The presence of a foreign body as the mesh may alter the wound healing process . Host reactions following implantation of biomaterials starts with blood/materials interactions and with provisional matrix formation, constituted by plasma proteins . The progression of events is characterized by the extravasation and migration of monocytes/macrophages at the implant site with the release of cytokines, chemokines, growth and angiogenic factors etc.
Biomaterials immediately and spontaneously acquire a layer of host proteins prior to interacting with host cells. Thus it is highly probable that the types, levels, and surface conformations of the adsorbed proteins are critical determinants of the tissue reaction to such implants . Conversely, the types, concentrations, and conformations of these surface-adsorbed proteins are dependent on biomaterial surface properties that dictate adhesion and survival of cells, especially monocytes and macrophages, on protein-coated surfaces .
The interaction of adsorbed proteins with adhesion receptors present on inflammatory cell populations, constitutes the major cellular recognition system for implantable synthetic materials. The presence of adsorbed proteins such as albumin, fibrinogen, complement, fibronectin, vitronectin, γ globulin and others, modulate host inflammatory cell interactions and adhesion and thus are linked to subsequent inflammatory and wound healing responses [12, 13].
The acute inflammatory response with biomaterials usually resolves quickly, in less than one week, depending on the extent of injury at the implant site. If present high levels and especially for prolonged periods of time may have a detrimental effect on healing .
The evaluation of some inflammatory response markers, in the drained fluid, allows us to better assess the events that follow a surgical wound . However, the presence of a drain can itself modify the profiles of cytokines and wound healing. On the other hand, the levels of cytokines secreated near the surgical wound can be determined only by using the drainage, because the study of drain fluid is still the best clinical surrogate marker of healing . Knowing the dynamic and the secretion profiles of different factors involved in the wound healing process at the site of surgical operation seems to be important because these soluble mediators play a crucial role in the pathophysiology of wound healing, as well as being popular target in the modification of the repair response .
This study shows that the inflammatory reaction differs in the subcutaneous and in the near-prosthetic space. High levels of anti-inflammatory interleukins (IL-10 and IL-1ra), and low levels of pro-inflammatory interleukin (IL-1) and CRP were detected in the DS fluid. Contrarily, in the DM fluid a low levels of anti-inflammatory interleukins and high levels of pro-inflammatory interleukin (IL-1) were observed.
In the DM fluid the elevated levels of pro-inflammatory cytokines promoted both a systemic and local inflammatory response directly or indirectly, causing fibro-proliferative lesions and maintaining inflammatory reaction and tissue scaring . On the contrary, the higher IL-1ra and IL-10 production in DS fluid indicates that the inflammatory response is attenuated by the inhibitory activity of these anti-inflammatory cytokines [18–20]. The early production of IL-1, followed by its decrease by post-operative day, is in line with the essential role of this cytokine in the healing process because it increases collagen synthesis and stimulates keratinocytes and fibroblast growth .
Some studies indicate that a more intense acute inflammatory response determines the formation of strong scar tissue. Marois et al.  observed that a more intense inflammatory reaction early after implantation, stimulates significantly greater tissue in-growth and integration. Junge et al.  observed in experimental study on animal model after implantation of mesh, that the lesser degree of reaction was followed by less connective tissue formation and a higher partial volume of fat tissue.
It has been commonly observed in clinical practice of the patients, who previously underwent prosthetic incisional hernia repair with sublay technique, that the preparation of subcutaneous space results more easy and feasible with respect to the dissection of the space where there is the mesh, because in this case a strong scar tissue is represented.
The incidence of seroma after incisional hernia repair is high, reaching values of 3% . The reasons for this are not known, however, high BMI, lowered preoperative serum concentration of total protein and albumin and high serum concentration of IL-1-RA are related to an elevated risk for postoperative seroma formation . In this study, the small number of patients studied and the absence of seroma does not allow us to correlate the inflammatory response and the amount of fluid drained with the development of seroma. A significant reduction of pH values was detected in DM fluid only on POD-4. The pH value within the wound-milieu indirectly and directly influences all biochemical reactions which take place in the healing process. It could be proven that wound healing is correlated to wound pH changes, as they can lead to an inhibition of endogenous enzymes [25, 26], such as an inactivation of fibroblast bindering its wound healing activity . For more than three decades the common assumption amongst physicians was that a low pH value, as found in normal skin, is favorable for wound healing. Recent investigation showed that the wound pH is indeed potent influential factor in the healing process . A significant reduction in pH is associated with the formation of seroma  and the stabilization of the pH values can reduce the adverse tissue reaction .