## 1 Introduction  
Skin is the largest organ of the human body, with distinct functions, such as protecting other organs from pathogeneses invasion, dehydration, mechanical impacts, radiation, and chemicals. Skin also serves to regulate body temperature, is an integral part of the sensory system, and acts as a reservoir for Vitamin D synthesis [1; 2]. Therefore, any skin damage must be treated appropriately, not only for the visual appearance but also to recover its functions, as mentioned above. Accordingly, specific consideration has been dedicated to developing proper wound-care/healing biomaterials/structures [3]. It is estimated that the global wound-care market reaches 22 billion US dollars by 2022 from the current share of 18.35 billion dollars, with a Global Compound Annual Growth Rate (CAGR) of 3.7% [4]. Moreover, out of various commercial wound-care/biomaterials, wound-dressings are the most prevalent. Different forms of wound-dressing biomaterials have been developed, such as transparent adhesive bandages, medicated bandages, hydrogel dressings, foams dressings, hydrocolloid dressings, and film dressings [5; 6; 7].  
From another perspective, wound-dressings can be categorized as passive, active, and interactive wound-dressings [8]. Passive dressings simply serve as a protective barrier and do not intervene in the healing process. Functional dressings provide a moist environment and facilitate the healing process. On the other hand, interactive wound-dressings provide a moist environment and interact with the wound bed components to further enhance the healing process [9; 10]. For instance, interactive dressings can adjust moisture retention, reduce microorganism colonization, improve collagen matrix formation, modulate inflammatory responses, reduce exudate levels, and protect epithelialization.  
Moreover, various types of bioactive substances have been implemented in the interactive dressings, such as anti-microbial, anti-inflammatory, and wound-healing agents. In addition to the structure, the composition of wound-dressings is another determinant factor. Wound-dressings have been made from different natural, synthetic, and semi-synthetic polymers. Among them, natural polymers have attracted more attention due to toxicity issues and, in most cases, more abundance [11; 12].  
It is crucial for an ideal wound-dressing to be biocompatible and to match in vivo physicochemical properties. While most natural polymers are biocompatible, they often have weak mechanical properties and low processability [13; 14]. Cellulose-based biomaterials not only have negligible biocompatibility, but also tunable physical, chemical, and mechanical properties. Various types of wound-dressing have been developed from cellulose-based biomaterials and exhibited promising results [15; 16].  
This review's primary focus is to provide a comprehensive assessment of cellulose-based biomaterials' studies as wound-dressing materials. We first elucidate the wound-dressings' role in the wound-healing process and then discuss the challenges regarding the wound-healing process and ideal wound-dressing requirements. Finally, cellulose-based wound-dressings are reviewed, their challenges are discussed, and practical perspectives are presented.