# Sericin for Tissue Engineering
## 3 Sericin and Tissue Engineering  
### Sericin for Burn Dressing  
Wound healing is a dynamic and complex process involving a highly organized and coordinated series of events [30; 87]. Theses complex events occur in four overlapping phases: hemostasis, inflammation, proliferation, and remodeling [30; 87; 88; 89]. Chronic wounds such as burns, diabetic wounds, and ulcers result in tissue injury, which becomes irreparable within a typical time period due to disturbance by various factors that prolong one or more of the four normal healing phases [87; 90]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Extraction Technique** & **Molecular Weight** & **Biological Activity** & **Reference** \\ \hline Autoclaving at 120 °C for 60 min & 25–150 kDa & Sericin extracted using urea exhibited & \\
1.25\% citric acid solution heated for 30 min & 50–150 kDa & the highest cell toxicity and the lowest & \\
0.5\% Na\({}_{2}\)CO\({}_{3}\) solution heated for 30 min & 15–75 kDa & induction of collagen production, while & \\
0.5\% Na\({}_{2}\)CO\({}_{3}\) solution heated for 30 min & 15–75 kDa & sericin extracted by the autoclaving & [64] \\
8 M urea for 30 min followed by heating at & & method showed the lowest cell toxicity & \\
85 °C for 30 min & & and the highest induction of & \\ \hline Autoclaving at 120 °C for 60 min & 35–150 kDa & collagen production. & \\
1.25\% citric acid solution heated for 30 min & 35–150 kDa & Compared to other extraction methods, & \\
0.5\% Na\({}_{2}\)CO\({}_{3}\) solution heated for 30 min & 15–75 kDa & sericin extracted using urea exhibited & [63] \\
8 M urea for 30 min followed by heating at & from 10 to \(>\)225 kDa & the highest antiprosinsnive activity. & [64] \\
85 °C for 30 min & & & \\ \hline Autoclaving at 120 °C for 20 min & smear & & \\
1.25\% citric acid solution heated for 30 min & smear & & Sericin extracted by the & \\
0.5\% Na\({}_{2}\)CO\({}_{3}\) solution heated for 30 min & smear & & \\
8 M urea for 30 min followed by heating at & & & \\
85 °C for 30 min & & & \\
0.02 M Na\({}_{2}\)CO\({}_{3}\) solution heated for 30 min & smear & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Molecular weight and biological activity of sericin according to the degumming method used. A burn is a tissue lesion characterized by changes varying from local erythema to complete destruction of the affected structure [91]. Burns are associated with significant mortality and disability, multiple surgeries, longer period of hospitalization and rehabilitation, and high medical costs [92]. The purpose of managing and treating burns is to induce epithelialization as quickly as possible for prevention of infection and reduction of functional and aesthetic sequelae [91]. Burns often lead to sepsis; hence, topical antimicrobial agents are always prophylactically administered to prevent the complications of infections [92]. Silk sericin has been directly used in regenerative medicine to maintain the proliferation of keratinocytes and fibroblasts during the wound healing process [93]. It can induce fibroblast proliferation and collagen production without the activation of pro-inflammatory cytokines [64; 68; 94; 95]. Further, it can be formulated and used as a wound dressing or cream to control wound infection [30] and employed to treat burns, reduce scarring, and prevent infection [91]. The antioxidant activity of silk sericin may help in the scavenging of ROS generated in chronic wounds. Therefore, sericin-containing substances may prevent the prolonged inflammation of chronic wounds and help in rapid healing by turning the wound healing process into a proliferative phase [96; 97]. Both a sericin cream and a cream combining sericin with silver sulfadiazine promoted healing of full-thickness burn wounds in rats [95]. In addition, clinical studies have shown that a cream containing silk sericin in combination with silver sulfadiazine is safe and beneficial for treating burns [93].