gms | German Medical Science

Stem cell based therapy offers promising therapeutic options in regenerative medicine and various tissues have been described for their stem cell niches. Since Zuk et al. first described stem cells from adipose tissue ten years ago [1] many studies demonstrated their potential to differentiate into various cell lines. The fraction of regenerative cells in adipose tissue has been described to be similar to bone marrow or even exceed it by the factor of 200–300 [2], [3]. An average of 10⁶ adipose derived stem cells (ASCs) can be isolated from 100 cc of aspirated adipose tissue [4]. The main advantage of ASCs is the abundant availability of the adipose tissue in most patients as well less limited morbidity associated with collection of the source tissue [5].

ASCs have been reported to secrete angiogentic and anti-apoptotice factors [6], and have the potential to differentiate into endothelial cells and become incorporated into vessels to promote neovascularisation [7], [8].

A positive effect in postmyocardial heart function of ASCs has been found in animal experiments [9]. Furthermore it has been described that ASCs are able to differentiate into chondrocytes [10]. An ASC-based regenerative therapy has also been shown to ameliorate soft tissue defects and improve skin quality [11]. Radiation dermatopathy has also been successfully treated in humans by stem cell augmented fat transplantation [12].

In order to use autogenous stem cells from adipose tissue under consideration of current regulations, a closed isolation system is needed located next to the patient.

The Celution^® system has been invented by Cytori Therapeutics Inc. (San Diego, CA, USA) and is available on the European market. Under sterile conditions the Celution^® system allows processing of lipoaspirate, gained from liposuction, in the operating room; the risk of contamination and destruction of the cells like on the transport to an outside laboratory is minimized. The automated process offers the possibility for standardized and reproducible isolation. In addition to augmented fat grafts in aesthetic surgery, adipose derived stem cells via such a process also open the door for other novel reconstructive applications such as:

1.

contracted or adherent scars,

2.

contour irregularities of the body surface,

3.

chronic wounds.

In this paper, we present our preliminary experience with ASC augmented fat grafting in reconstructive surgery.

We present four cases of ASC augmented fat grafting in reconstructive patients with volume deficits, scars or wound breakdown.

Liposuction was used for retrieval of fat grafts and adipose tissue for isolation of ASC and stromal fraction. Tumescent solution containing 1 cc Epinephrine 1:1,000 and 10 cc sodiumbicarbonate 8.4% each 1,000 cc saline 0.9% was injected 20 minutes before liposuction. The suction lipectomy was performed manually using blunt cannulas with three holes (Figure 1 [Fig. 1]).

The protocol for isolation of the ASC rich stromal fraction is based on the method described by Zuk et al , and employs Celution^® by Cytori Therapeutics Inc., San Diego, CA, USA (Figure 2 [Fig. 2]). The lipoaspirate is transferred directly into the Celution^® System (Figure 3 [Fig. 3]). After washing and depletion of erythrocytes, enzymatic digestion with several collagenases (Celase^®) is started inside the chamber of the system. In the beginning a maximum of 260 cc of lipoaspirate (now after an update 360 cc) can be processed per aliquot in the Celution system. The enzymatically freed stromal fraction, containing the ASCs, is then transferred automatically to the integrated centrifuge. Several cycles of centrifugation and washing of the cells follow, resulting in approximately 5 cc of ASC rich stromal fraction no matter how much lipoaspirate has been injected [13].

The required volume of fat graft for fat transplantation is gained once more by liposuction and placed in the system to be washed and mixed with the 5 cc of ASCs and stromal fraction (Figure 4 [Fig. 4], Figure 5 [Fig. 5]). The ASC augmented fat graft may now be taken from the system to be transplanted. Besides adipocytes, ACSs, endothelial progenitor cells and endothelial cells, pericytes, vascular smooth muscle cells, hematopoietic like stem cells, leukocytes and lymphocytes are transplanted [13].

Using a special applicator, called Celbrush^® (Figure 6 [Fig. 6]), the ASC augmented fat graft is injected in small aliquots in a fan shape pattern into the recipient tissue via 1–3 mm drops per 3 mm injection cannulas.

A 58-year-old female patient after skin sparing mastectomy and adjuvant radiotherapy had persistent contour deformity and scarring of the right breast (Figure 7 [Fig. 7]) after failed attempts of reconstruction with a TRAM flap and a pedicled latissimus dorsi muscle flap elsewhere. There was a preoperative volume deficiency of approximately 150 cc on the right side which was addressed by fat grafting in the above describe manner in addition to corrective plastic surgery of the breast with reconstruction of the infra mammary fold. Adipose tissue was aspirated from bilateral gluteal regions and 260 cc of lipoaspirate were loaded into the Celution^® system and processed to 5 cc of stemcell-stromacell solution. This 5 cc were mixed with 145 cc of freshly aspirated liposaspirate and a total of 150 cc were injected into the patient. Postoperatively the shape of her breast was ameliorated (Figure 8 [Fig. 8]).

A 47-year-old female patient with sclerodermia presented with a chronic ulcer overlying the partially necrotic achilles tendon. Attempts of reconstruction with skin grafts and a microvascular parascapular flap elsewhere had failed. After stabilisation of the wound bed by applying allogenic skin grafts (Figure 9 [Fig. 9]), the wound was laser debrided and pure 5 cc stromal cell fraction processed from 260 cc of lipoaspirate was applied without resuspension in additional fat graft. In this case the stromal fraction was mixed with autologous keratinocytes processed intraoperatively with the ReCell^® Kit. This cell suspension was sprayed on the wound bed and covered with allogenous skin to limit mechanical shearing of the cells.

Two months postoperative the wound was reduced in size and depth, but a sufficient epithelization was not archived (Figure 10 [Fig. 10]).

A 27-year-old female patient presented with a scar formation of the superior aspect of the left breast and shoulder due to a thermal injury as a child. To reduce and soften the scar as well as to reconstruct the volume deficiency of the left breast, implantation of skin expanders were combined with autologous ASC augmented fat transplantation to the left breast (Figure 11 [Fig. 11]). Preoperative radiological imaging including mammography and MRI revealed no suspicious lesions or tumors within the breast tissue. The fat graft was harvested by liposuction from the abdomen and 135 cc were processed with the Celution^® system. Fat grafting of 70 cc lipoaspirate augmented with 5 cc stromal fraction was performed to reconstruct the left mamma and to soften the scars. The expanders were explanted in time and resection of large areas of the scar could be done. The patients reports about softening of the scars and reduction of the contracture. Six month after surgery the asymmetry of the breasts was reduced and the volume deficiency of the left breast corrected (Figure 12 [Fig. 12]).

A 24-year-old female patient presented with a soft tissue defect of the left calf above the tibia (Figure 13 [Fig. 13]). A segment graft of the tibia had been performed following a resection of a osteofibrotic dysplasia in childhood. The course was complicated by an osteitis requiring several debridements. Examination shows an adherent scar and the asymmetry of her calf. Six months prior to ASC augmented fat grating, a conventional fat grafting procedure was performed, without sufficient volume augmentation (Figure 13 [Fig. 13]). In this patient 160 cc of lipoaspirate were processed with the Celution^® system. After ASC augmented fat grafting with 50 cc the volume augmentation is more evident. Four months postoperatively, the improvement in volume deficiency is still maintained (Figure 14 [Fig. 14]).

The patients have been followed up for an average of 12 months (8–15 months) and no side effects of the therapy appeared.

Treatment of our series of patients with ASC augmented fat grafting resulted in satisfying results. The angiogenetic effect of ASCs [7], [8] may play an important adjunctive role in the survival of transplanted adipose tissue. In 1893 Neuber reported, that the survival of fat grafts is related to the size of transplanted pieces [14]. Based on the finding that smaller pieces have a better survival Coleman developed his method of lipostructural autologous lipotransfer [15]. The angiogenetic potential of an ASC augmented fat graft supports the vitality and survival of the transplanted fat [16].

A major advantage of ASCs processed with the Celution^® system is the immediate availability of the cells, obviating the need for time consuming processing in the laboratory as in instances of bone marrow preparations for clinical use. Such conventional cultivation methods are significantly more expensive and may in fact cause clinically relevant changes in cell biology [17]. Furthermore the amount of stem cells to be gained from bone marrow is limited, and associated with side effects for the donor. Stimulation medication before donation may not be free of any risks. These restrictions of bone marrow derived stem cells have led to an emerging interest in ASCs. More recently, adipose tissue has been recognized as a potentially bountiful source for various types of progenitor cells [18], [19].

Like bone marrow, adipose tissue develops from mesodermal tissue and gains volume by proliferation of progenitor cells and cell growth [16]. The progenitor cells, morphologically similar to fibroblast, have the ability of chondrogenous, adipogenous, neurogenous, osteogenous and myogenous differentiation [20], [21], [22].

Other factors suggest that adipose tissue may be a more viable source for progenitor cells. The harvesting of adipose tissue is identical to liposuction, a simple, widely utilized clinical procedure with a long track record of relative safety. The fraction of pluripotent cells in adipose tissue is also higher compared to that of bone marrow [4], [21], [23]. Combined with the abundance of fatty tissue in most patients makes adipose tissue an attractive source for the harvesting of abundant progenitor cells.

Cytori presents data that 100 cc of adipose tissue processed with the Celution^® system result in 25 to 40 millions of cells. Lin et al. demonstrated that an average of 295,176 cells can be isolated from 1 cc of adipose tissue applying the Celution^® system [13]. Suga et al. present data that one cm³ adipose tissue consist of 1 million adypocytes, 1 million ASCs, 1 million endothelial cells and 1 to 2 millions other cells like blood cells [24].

Results of injection of pure isolated stromal cells without accompanying fat tissue have shown insufficient volume augmentation. The Celution^® approach adds the isolated stromal fraction to unprocessed plain fat grafts. The addition of additional adipose tissue to the graft not only augments the volume of the injectant, but also adds transferred adipose cells, which stand to benefit the most from the angiogenic effects of the ASCs. Animal studies have shown a 2.5 times higher fat preservation rate of this approach in comparison to unprocessed plain fat grafts [16].

Kim et al. present nice results in their actual study about fat cells differentiated from ASCs [25]. ASCs were isolated from lipoaspirates from the abdominal region and were cultivated for 24 to 26 days to correct soft tissue defects and facial scars. Progress control has been performed with 3 D scanners and appealing long tern results were demonstrated [25].

The cases presented in our series are first examples for regenerative therapies. Various therapeutic options of ASCs have been evaluated in animal models. In an ischemia reperfusion model the renoprotective ability of ASCs was demonstrated [26]. Flaps [27] or hind limb [28] perfusion could be ameliorated by ASCs and diabetic ulcera have been treated successfully [29]. Even functional improvement after myocardial [9] or cerebral infarction [30] have been described. Further research is compressively mentioned in the review papers by Mizuno [31], [32].

In clinical settings stem cell augmented fat transplantation or ASCs therapy has been performed in the treatment of facial lipoatrophy [33], breast augmentation [34], without giving a concrete volume survival rate, and perianal fistulas [35]. In a study consisting of 30 patients ASCs have been used for regenerative therapy of facial hemiatrophy, pectus excavatus, gluteal soft tissue defects and for breast reconstruction [36].

Rigotti reported promising results with ASC augmented fat grafts in the treatment of radiation-induced ulcers, although multiple fat grafts in combination with skin grafts was necessary [12]. In 19 of 20 patients an amelioration of the wounds were observed during an 18- to 31-months follow-up time. The high angiogenetic power of ASCs is discussed to be responsible for this finding. Creation of new vessels will consequently lead to an improved vascularisation, providing a more hospitable bed for the transferred adipose cells. In two other patients treated with ASC augmented fat grafts in our clinic, we were able to detect an improved tissue oxygenation by laser Doppler after treatment of radiation ulcer [37].

The angiogenetic potential of ASCs may be useful in breast augmentation and -reconstruction [16], [38] as it might lead to a superior volume survival – theoretically. This angiogenetic potential is especially in breast surgery socialized with the risk of tumour induction. There should be an awareness of this possible side effect, even if the in vitro findings of tumour induction for example in prostate tumours [39] or the interaction of ASCs with breast tumour cells [40] can not be transferred into clinical use directly.

Overall we found out that ASC augmented fat grafts are especially successful if vital adipose tissue is available at the recipient site and sufficient covering of the graft by local skin is given. It may be that there is a threshold level of native perfusion required in the recipient bed for the angiogenic effects of ASCs to take effect on the co-transplanted adipose tissue. As an extreme example, no amount of ASC-induced angiogenic augmentation would have an effect on a gangrenous wound. Furthermore, chronic inflammation likely blunts the effect of the anabolic potential of ASCs and in fact promotes resportion of any transplanted fat. This observation is clinically supported by the fact that wounds which have been made more quiescent in regards with inflammation with even temporary cadaveric skin grafts tend to do better with fat grafts in general.

The first examples of this work point up the potential of ASCs in regenerative medicine and open the door for further application in clinical reconstructive work.

In Germany the clinical use of stem cell enhanced fat grafts for regenerative therapy and not for simple augmentation of adipose tissue is regulated by the German drug law (Arzneimittelgesetz) part 3 § 20 b and c.

The authors declare that they have no competing interests.