**3.** *In vivo* **models for assessing wound healing activity**

or without the loss of underlying connective tissue [1, 2]. Wounds that are most difficult to heal include delayed acute wounds and chronic wounds. Current estimates indicate that nearly 6 million people suffer from chronic wounds worldwide [3, 4]. Foot and leg ulcer is a common disorder, and approximately 1% of the European population suffers from such chronic and recurrent ulceration [3, 5]. Non‐healing or chronic wounds result in enormous health care expenditures, with the total cost estimated at more than \$3 billion *per* year [3, 4]. Wounds such as injuries, cuts, pressure, diabetic, burns, gastric and duodenal ulcers continue to have severe impact on the cost of health care to patients as well as their families, dependents and health care

Over the last decades, the search for newer and potent agents from nature (plants, marine environment, fungi and other microorganisms) to manage chronic wounds especially, in patients with underlying metabolic disorders has increased immensely. This is mainly due to the high risk of loss of function, loss of mobility, amputations and huge financial cost as well as death in some cases associated with chronic wounds [6, 7]. The situation is also compounded by the increase in the number of non‐communicable diseases such as diabetes and ulcers and longer life expectancy in most developed countries where the prevalence and impact of chronic

Most chronic wounds are ulcers that are associated with ischemia, diabetes mellitus, venous stasis disease, or pressure. Between 70% and 80% of people living in the developing countries especially in Africa and Asia depend on herbal medicine for their health needs including wounds, infectious and metabolic diseases [5]. For some time now, there have been increased use of herbal and natural products for the management and treatment of various disease conditions among people in the developed countries including the United States, Europe and

With respect to the use of medicinal plants and natural products for the treatment of various diseases including metabolic and infectious diseases, specific diagnoses using various modern tools and equipment are not normally made but the treatment is based on the signs and symptoms of the diseases with which these products have been used for over a long period of

This section highlights the importance of medicinal plants and natural products as a major source of wound healing agents with the potential to be developed into phytotherapeutic agents to treat and/or manage wounds and their associated complications. This will also provide a starting point for future studies aimed at isolation, purification, and characterization of bioactive compounds present in these plants as well as exploring the underlying pharmacological mechanisms of action and potential niche market of these medicinal plants

**2. Properties of a good wound healing agent from herbal or natural product**

Wound healing agents are agents that can stimulate fibroblast proliferation, induce keratino‐ cytes proliferation and differentiation, increase collagen formation, exhibit antimicrobial,

institutions globally with increasing aging population.

484 Wound Healing - New insights into Ancient Challenges

wounds are on the increase [8].

time with successful treatment outcomes.

and natural products.

Japan.

*In vivo* models include both artificial and tissue models. Artificial models include subcutaneous chamber/sponges and subcutaneous tubes. Tissue models such as excision wounds, incision wounds, superficial wounds, dead space and burn wounds are usually used to determine the degree of re-epithelialization, collagenation, neovascularization and tensile or breaking strength of wounds [11–13]. Models such as rabbit ear chamber, the hamster cheek pouch, the rabbit corneal pocket and the chick chorioallantoic membrane can also be employed to investigate the extent of re-epithelialization, neovascularization and dermal reconstitution [14].
